Paper pub. date
January 1999
ISBN 9780870714719 (paperback)
6 x 9 inches, 424 pages. Illustrations. Color photos. Maps. Keys. Illustrated glossary. Index.
Out of Print

Flora of Steens Mountain

Donald H. Mansfield

A significant contribution to Oregon and Great Basin flora, this comprehensive field guide identifies plants of Steens Mountain and surrounding areas in southeastern Oregon, including Malheur National Wildlife Refuge, Diamond Craters, and the Alvord Desert. It also provides reasonable coverage for plants in southwestern Idaho and northern Nevada.

Steens Mountain, the northern most fault-block mountain range in the Great Basin, is a botanically rich region that in recent years has become a popular destination for outdoor enthusiasts and naturalists. This concise guide is designed to be carried into the field and used to identify vascular plants in their natural habitats. The book includes simple yet accurate keys for identification. In addition to line drawings of more than 200 species, the book features a section of color photographs.

Introductory chapters include general information on the area's geology, vegetation, and natural history, as well as Native American use of plants, early botanical exploration, rare plants, and guidelines for collecting.

Flora of Steens Mountain offers an invaluable resource for amateur and professional botanists, as well as anyone seeking to better understand the region's rich and diverse plant life.

About the author

Donald H. Mansfield is professor of biology at Albertson College of Idaho and curator of the Harold M. Tucker Herbarium.

Read more about this author
  • Acknowledgments
  • Introduction
    • Organization of the Book
    • Geographical Region Covered by the Book
    • Steens Mountain
    • Geologic and Biogeographic History
    • Floristic Overview of Steens Mountain
    • Vegetation Zones and Plant Communities
    • What Makes a Plant Rare?
    • Rare Plants of Steens Mountain
    • Brief History of Botanical Exploration on Steens
    • How to Use the Keys in This Book
    • How to Make a Plant Collection
    • Scientific Names
    • Common Names
  • Keys to the Flora of Steens Mountain
    • Key to Families
    • Families of Ferns and Fern Allies
    • Families of Gymnosperms
    • Families of Angiosperms
  • Glossary
  • Illustrations
  • Selected References
  • Index of Families
  • Index of Genera
  • Index of Common Names


Steens Mountain, Malheur National Wildlife Refuge, and the Alvord Desert have become popular destinations for a variety of outdoor enthusiasts and naturalists. Wildflower displays of Steens Mountain, the desert flora of the Alvord and Harney basins, and the variety of landscapes in the region attract interest from both the botanist and nonbotanist alike. This book is designed to serve the needs of both the amateur and the professional, the beginner and the more experienced. There will be many who have some familiarity with the plants "back home" but who are intrigued by the strange variety of desert, montane, and alpine plants here at Steens Mountain and its surrounding basins. There may be some who have never "keyed" a plant before but who are frustrated that the picture guides never seem to include the plants that are right here, right now. There will be some who have a casual or professional interest in the wildlife, or the ranches, or the land or stream management, or any of the endless variety of outdoor occupations or avocations in which there is a need to have some familiarity with the plants around us. There may be some for whom botany may be a hobby, an excuse to experience the grandeur of nature in solitude and observe there the miraculous variations in plant form.

The first step in understanding the incredible diversity of plant life around us is the identification of species. We now know very little about the flora of Steens Mountain beyond the identity of species here. Many of the more interesting questions we might ask require first that we simply know what is here and be able to put a name to it. How are the plants uniquely adapted to living where they do? What animals use them and how? How did Native Americans use these plants? How did these plants get here? Much of what we know about plants has resulted from investigations by "amateurs." New horizons and insights await those with the patience to observe carefully and inquire about the plants around them. What will surely follow with knowledge is appreciation and understanding.

By writing a book on the flora of any region, one runs the risk of giving the impression that the floristic study of the area is "finished." The flora of Steens Mountain is certainly not finished. First, there will undoubtedly be more collections of plants not included now in the flora. It has been suggested that a flora can be "written" once 90% of its species are known. I have little doubt that we now are aware of at least 90% of the plant diversity on Steens Mountain. However, in the past decade not a year has passed in which I did not find something new to the area. Second, the nature of the diversity represented in herbaria such as the ones at Albertson College of Idaho, Oregon State University, or the New York Botanical Garden suggests the presence of many "fuzzy" areas in which further genetic study will be needed before all the kinds of plants are described from this region.

Organization of the Book

Following a brief introduction to the taxonomy of vascular plants and an overview of the geography, history, floristics, and vegetation of Steens Mountain, this book consists mainly of dichotomous keys (identification guides) to all of the vascular plants of southeastern Oregon in the vicinity of Steens Mountain. The book is designed to be used in the field to guide the motivated novice or professional in identifying ("keying") an unknown vascular plant specimen in hand. The book is organized to allow the user to identify a specimen at hand, first by the plant family (groups whose names end in "-aceae" and that include one or more genera), then by genus, and finally by species.

The plant species are keyed within genera, which are arranged alphabetically within families, which in turn are arranged alphabetically within three major groups: the seedless vascular plants (ferns and fern allies), the gymnosperms (conifers and relatives), and the angiosperms (flowering plants). This book does not include mosses, liverworts, algae, mushrooms, or related groups. The ferns and their allies are represented in the Steens flora by seven families in three divisions, all listed alphabetically in the first section. The gymnosperms are poorly represented here, with only three families (and only three genera), again alphabetical, in two divisions. There are eighty-six families of angiosperms in this flora. Families of both the monocots (class Monocotyledonae or Liliopsida) and dicots (class Dicotyledonae or Magnoliopsida) are listed together alphabetically to assist the novice, though this may at first be confusing to the experienced botanist familiar with keys that separate the families of these two classes. The key to all of the families precedes family descriptions and species keys. Alternate accepted family names are included in the headings and for each family.

Each family description includes general information about the family, ethnobotanical significance, recognition characteristics, and unique morphological features that will be used in the keys to distinguish among the species of that family. Following the family description is a key to the genera of the family found in the Steens flora. Genera are then listed alphabetically.

For each genus (in boldface type) the Greek, Latin, or honorific derivation of the name is given, followed by the key to all of the species in the genus that are found in our area. In large or important genera, additional ethnobotanical, biogeographical, morphological, or ecological information is included.

The species name is a binomial, consisting of a genus name (abbreviated as the first letter of the genus) followed by the specific epithet (the descriptor distinguishing a given species of the genus). The binomial is in boldface type, and the authority, the person who named and described the plant, follows the binomial. Adventives are noted with an asterisk (*). Common names are then provided.

About 25% of the species are illustrated. Figures are cited in boldface type after species names. Color plates are indicated by P1 in the same location. A number by each illustration indicates the factor by which it is magnified or reduced in relation to the living plant.

A short description of each species is intended to provide a mental image against which to evaluate the specimen being keyed. For each species, the distribution in the geographic area of this flora is provided, along with a brief summary of its global distribution. Elevations are in meters (a conversion chart is provided on the last page of the book). Refer to the map (Figure 1) on page 5 and see Table 1 for elevations of major landmarks. Note that high-elevation species may often exist at lower elevations in the canyons of the east side. Ethnobotanical uses are cited when known. For species in which more than one subspecies or variety is present, these are listed and their distinguishing characteristics noted.

Approximately 5% of all of the species in this flora are "rare" plants. When listed as rare by the Oregon Natural Heritage Program (ONHP), rarity is noted by citing the list on which it occurs in The Rare, Threatened, and Endangered Plants and Animals of Oregon, December 1998. When rare plants are encountered, they should be reported to the Oregon Natural Heritage Program office in Portland (503-731-3070).

For additional information about Steens Mountain flora, including photographs of many of the plant taxa, refer to the following web page: (

Geographic Region Covered by This Book

This book considers all vascular plants known to grow on Steens Mountain and in the surrounding basins (Alvord, Catlow, and Harney). It also treats plants suspected of growing in that area and many nearby plants. As such, the flora is well suited for the study of botany of southeastern Oregon and southwestern Idaho.

The area specifically covered by this book (Figure 1) lies entirely within the area bounded by 42015' and 43008'N latitude and 118008' and 1190W longitude. This area of approximately 5,000 km2 comprises most of the southern half of Harney County, Oregon. A small portion of Malheur County is included in the vicinity of Folly Farm. The gorges on the west and north of Steens Mountain drain gradually into the Malheur Marsh and ultimately Harney Lake, while the steep eastern escarpment is drained by several streams that find their way to the Alvord Desert or Pueblo Valley. Southwestern Steens Mountain drains west into the Catlow Valley.

The region referred to as "Steens Mountain" in this flora includes all of Steens Mountain from Long Hollow near Fields to Riddle Mountain east of Diamond, the entire Alvord basin, the Pueblo Valley, Catlow Rim and the eastern edge of the Catlow Valley, Diamond Craters, and the Malheur Marsh. The book also includes plants known to occur just outside of these boundaries and thus covers the Pueblo Mountains and Harney basin. The book will be generally useful in a much broader area that covers most of southeastern Oregon east of the high lava plains and south of the Blue Mountains and much of southwestern Idaho and northern Nevada.

Most readers will be using this book while gaining access to Steens Mountain along one of three main roads (see Figure 1): (a) the Steens Mountain Loop Road, (b) Highway 205 from Burns to Frenchglen to Fields, or (c) the Fields--Denio Highway from Folly Farm (Highway 78, 40 miles northwest of Burns junction) to Fields. Elevations are between 1,200 and 1,300 m (4,000 and 4,300 ft) along the Fields--Denio Highway. Approximate elevations of major landmarks are given in Table 1. Steens Mountain

Steens Mountain, the northernmost fault-block mountain range in the Great Basin, is unusual in four respects. First, large basins, approximately 1,200 m (4,000 ft) in elevation, isolate Steens Mountain (elevation 2,950 m or nearly 9,700 ft) from other high mountain ranges.

Minor peaks in the Blue Mountains, 200 km to the north, and Santa Rosa and Pine Forest Ranges, over 100 km to the south, are the closest mountainous areas rising above 2,700 m. Second, Steens Mountain has an extensive contiguous area of approximately 75 kM2 above 2,400 m (about 8,000 ft) elevation. The nearest ranges with this much alpine topography are the Cascade--Sierra Range over 350 km to the west and the Wallowa Range 320 km to the northeast. Steens Mountain is also the largest of the Great Basin ranges north of 400N latitude and west of 1160W longitude. Third, the northwestern portion of the Great Basin, north of 420N latitude, is unique in having less summer precipitation, more winter precipitation, and lower mean annual temperatures than the rest of the Great Basin. Finally, the subalpine vegetation is striking in its domination by aspens and its lack of coniferous tree species that clothe ranges of this size elsewhere in the western United States. The combination of isolation, extensive alpine topography, extreme climate, and unusual subalpine physiognomy results in a unique flora.

Steens Mountain (Steens) is at the geographic periphery of three regional floras: the Flora of the Pacific Northwest (Hitchcock and Cronquist 1973), The Jepson Manual: Higher Plants of California (Hickman 1993),and the Intermountain Flora (Barneby et al. 1990; Cronquist et al. 1972,1977,1984,1994,1997). As a result, the range of variation observed in the flora of Steens is quite different than that found in existing floristic treatments. The flora of the region is well-represented on Steens Mountain as a consequence of the extensive topographic variation spanning its nearly 1,800 m (6,000 ft) of relief. Thus, study of the Steens flora may provide insights into evolutionary systematics of the northern Great Basin and western North America.

Table 1. Elevations of Major Landmarks on and near Steens Mountain (1 m 3.279 ft; 1 ft = 0.305 m)
Road access Landmarks Elevations (approx.)
    m ft

Steens Loop Rd. Page Springs 1,300 4,200
  Rock Creek Reservoir 1,900 6,200
  Fish Lake 2,250 7,400
  Jackman Park 2,350 7,700
  Fish Creek spring (1 mi above
   Jackman Park)
2,450 8,000
  Kiger overlook turnoff 2,700 8,900
  Wildhorse/East Rim junction 2,900 9,550
  Rooster Combs 2,250 7,400
  Switchbacks overlooking bottom of Big Indian Gorge 2,025 6,650
  Blitzen River crossing 1,550 5,100
  Hwy 205 junction 1,400 4,600
Off Steens Loop Wildhorse parking area 2,900 9,500
  Wildhorse Lake 2,550 8,400
  Steens summit 2,950 9,700
Near Highway 205 Diamond Craters summit 1,450 4,700
  Frenchglen 1,300 4,200
  Roaring Springs (Catlow Valley) 1,400 4,600
  Long Hollow pass 1,700 5,600
  Fields 1,300 4,200

Geologic and Biogeographic History

A brief geological history of Steens Mountain is relevant to understanding the unique qualities of the Steens flora. The story begins about 30 million years ago, during the Oligocene Epoch, when the area was forested by a tropical flora. A widespread cooling trend ensued when the Cascade Range began to rise. By 20 to 25 million years ago (early Miocene), eastern Oregon was forested by a deciduous forest flora much like that in present-day Ohio or eastern China. Volcanic eruptions that occurred during this time produced the lowest layers of what is now Steens Mountain - the red, principally rhyolitic and tuffaceous Pike Creek Volcanic Series (23 million years old). The Alvord Creek Formation of tuffs and plant fossil-bearing lake-bed deposits formed approximately 21 million years ago in what appears today as the light-colored beds above Alvord Ranch. The Alvord Creek fossils tell us that annual precipitation at this time was about double the current rate and that mean annual temperatures were higher and with less drastic extremes. The andesitic and basaltic flows that today form the middle elevations of Steens (the Steens Mountain Volcanic Series) and the Steens Mountain Basalt that forms the present-day cliffs above 2,100 m (7,000 ft) flowed over the area from between 13 and 18 million years ago (mid-Miocene). Roughly 8 to 10 million years ago (late Miocene), faulting began and the Steens uplift commenced. By this time, the Sierra--Cascade Range had uplifted substantially, providing a rain shadow in southeastern Oregon. Together, these geological events resulted in a different regional climate and a greater diversity of habitats than had previously existed in the area. By about the end of the Miocene Epoch, the Great Basin floristic province had become established.

By 2 to 3 million years ago (late Pliocene) the climate was generally cool and moist, though drier than in earlier times and with less summer precipitation. Consequently, the regional flora continued to change, becoming more desert-or-steppe-like as new species emerged that were adapted to these new, more and climatic conditions. The past few million years have been characterized by alternating glacial and interglacial periods. Throughout these periods, continued erosion of the Steens massif has produced alluvial fans in the Alvord basin which have become confluent to form a gradual slope, called a "bajada," between the mountain and the floor of the Alvord Desert. Three geologically distinct periods of glaciation are evident on Steens Mountain. Initially, glacial ice covered nearly 300 km2 in the Fish Lake advance, filling or carving the major gorges--Big Indian, Little Blitzen, and Kiger. A second period (the Blitzen advance) was restricted to the canyons and covered about 130 km2, forming the headwalls of the major gorges. During the final and much smaller glacial advance, which ended no later than 12,000 to 13,000 years ago, the ice carved the smaller cirques that lie above 2,400 m (8,000 ft.), including South Fork Willow Creek and Big Alvord. The past 8,000 years in the northern Great Basin have been characterized by a drier climate and a corresponding loss of more moist-loving species from the region. On Steens Mountain a roughly twofold increase in sagebrush to grass pollen is observed between 5,500 and 8,000 years ago, indicating that this was the driest period of the Holocene on Steens.

During alternating glacial and interglacial periods of the past few million years, two main processes appear to have produced the modern distributions of plant species in the Great Basin. First, during cool, moist periods of glacial advance, species migrated down in elevation and/ or into the region from the north; during the warmer, drier interglacial periods, species migrated to higher elevations and/or into the region from the south. Second, montane "islands" probably lost species via local extinctions and gained species by immigration, according to the predictions of island biogeography theory. Based on the current affinity of the flora with Columbia Plateau, Great Basin, and Sierra Nevada floristic elements, it appears that the present flora of Steens originated with the regional flora primarily during the Pliocene. That is, most of the plants of Steens Mountain are distributed throughout the northern Intermountain region. The unique aspects of the Steens flora, those features that distinguish it from the rest of the region, seem to result from the local extinction, migration, and speciation peculiarities during the geologically recent Quaternary Period. Today, annual precipitation at lower elevations is 220 to 280 mm (approximately 9 to 11 inches) increasing to 700 mm (28 inches) or more at the higher elevations.

Many of the alpine species found on Steens Mountain are "Rocky Mountain" species found to the northeast of this area in the Wallowa Mountains or the mountains of central Idaho. Such species include Sedum debile, Arnica rydbergii, Carex nova, Saxifraga adscendens, Caltha leptosepala var. leptosepala, Salix glauca var. villosa, Voydia serotina, and Polemonium viscosum. Another group is "Sierra Nevada" species, found to the southwest of here with their northeastern limits in this range. This group includes Salix orestera, Carexfilifolia, Potentilla glandulosa var. nevadensis, Claytonia nevadensis, and Dodecatheon alpinum. The presence of these groups of species at the edge of their ranges implies that Steens has had affinity with both the Rocky Mountain flora and the Sierra Nevada flora.

In examining all of the many genera of Steens plants, I have been continually amazed at how many groups show one of three common patterns: Consider 2 species in a genus known for hybridization and "leaky" species boundaries (Salix, Arnica, Saxifraga, Potentilla, Aster, etc.). Species A, at the western limit of a Rocky Mountain distribution, and species B, at the northeastern limit of its Sierra Nevada distribution, migrate to the alpine area on Steens, isolated from their other populations. Now, after several millennia and considerable climatic fluctuations, one of the following has occurred. 1) One species is left but it hardly resembles material from the rest of the range. (There are probably several varieties yet to be described on Steens.) 2) Two species are evident but they are really nothing more than extremes of a continuous distribution of variation that spans the original 2 species (many varietal or species distinctions seen elsewhere break down here, with elements of both varieties or species apparent). 3) One species remains that is clearly like the species elsewhere in its distribution, except it occasionally shows up with some atypical genes resulting from introgression and resembling the other species presumably now locally extinct.

Floristic Overview of Steens Mountain

The vascular flora of Steens Mountain includes 1,150 taxa (Table 2) and represents well the approximately 4,500 vascular plant taxa in Oregon.

Of these taxa, 120 (10.1 %) are exotics (post-settlement introductions to the area). Six are endemic to Steens Mountain or Steens and nearby ranges, and 26 additional taxa are regional endemics restricted in distribution to eastern Oregon, southwestern Idaho, northern Nevada, and northeastern California, or some part thereof. At least 154 taxa (13.2%) are at or near the edge of their ranges in Steens. Seventy-six principally basin taxa are near the northern edge of their Great Basin distributions. Twenty-nine taxa have Rocky Mountain or southern Idaho distributions and are near the western or southwestern edge of their ranges on Steens Mountain. Twenty taxa are principally Sierra n and reach the northeast limit of their ranges here. Twelve have Sierra/ Cascade distributions with their easternmost populations in this area. Seventeen boreal or more northern taxa reach the southern limit of their range here. With 1,085 species, the Steens Mountain flora is larger than any of the 96 local floras throughout the western United States cited by McLaughlin (1986, 1989).

The largest families (Table 3) and genera (Table 4) in the flora are tallied below.

Table 2. Summary of the vascular flora of Steens Mountain, Oregon.
Taxon Families Genera Species Subspecific taxa

Ferns and fern allies  7 11 20 20
Pinophyta  3  3  5  5
Magnoliopsida 72 318 825 881
Liliopsida 14 83 235 244
   Total 96 415 1,085 1,150

Table 3. The largest families in the flora of Steens Mountain.
Family Number of species Number of varieties/subspecies

Asteraceae 163 183
Poaceae 104 111
Brassicaceae 67 73
Scrophulariaceae 52 53
Fabaceae 46 53
Cyperaceae 51 52
Polygonaceae 35 42

Table 4. The largest genera in the flora of Steens Mountain.
Genus Number of species Number of varieties/subspecies

Carex 38 38
Eriogonum 17 22
Salix 20 20
Engeron 17 18
Juncus 17 18
Potentilla 14 16
Epilobium 13 15
Luptnus 12 15
Poa 12 15

Vegetation Zones and Plant Communities

The vegetation of Steens Mountain can be divided into five zones that correspond to the vegetation zonation concepts of Holmgren (1972) with modifications relevant to Steens Mountain (McKenzie 1982; Urban 1973).

Shadscale/marsh zone (-1,300 m). Alkaline desert scrub vegetation of the Alvord Desert below approximately 1,300 m is dominated by Atriplex confertifolia (shadscale), A. canescens (fourwing saltbush), Sarcobatus vermiculatus (greasewood), Grayia spinosa (spiny hopsage), Distichlis spicata var. stricta (saltgrass), and other halophytes. Well-drained soils are dominated by such species as Artemisia tridentata sst. tridentata (basin big sagebrush), Leymus cinereus (basin wild rye), Ericameria nauseosa (common rabbitbrush), E. viscidiflora (green rabbitbrush), and other nonhalophytic species. This vegetation zone is also in the Harney Basin and, at a slightly higher elevation, the Catlow Valley. However, most of the Harney Basin at the base of Steens Mountain contains the freshwater Malheur Marsh. Marshes throughout the three basins are dominated by Scirpus acutus (hardstem bulrush), Typha latifolia (broadleaf cattail), and, depending on water depth and locality, a variety of other emergent taxa. Ash outcrops, sand dunes, barren clay soils, and a variety of wetlands including riparian meadows and woodlands, ponds, and hot springs are also present in this zone in the three basins.

Sagebrush zone (1,300-1,650 m). The lower flanks of Steens Mountain, from about 1,300 to 1,650 m, are dominated by Artemisia tridentata ssp. vaseyana (mountain big sagebrush), A. arbuscula (low sagebrush), in the shallower soils, Ericameria nauseosa var. hololeuca (common rabbitbrush), and a variety of grasses and forbs including Pseudoroegneria spicata (bluebunch wheatgrass), Achnatherum spp. (needlegrasses), Lupinus spp. Lupines), Perideridia spp. (yampas), and Lomatium spp. (biscuitroots). Most of the Artemisia tridentata ssp. wyomingensis (Wyoming big sagebrush) habitat on the west side of Steens has been planted in Agropyron cristatum (crested wheatgrass). Juniperus occidentalis (western juniper) extends into this zone from above along basaltic fractures occupied by Ribes cereum (wax currant), Holodiscus dumosus (desert spray) and other shrubs. Riparian woodlands dominated by Salix spp. (willows), Alnus incana (mountain alder), Betula occidentalis (water birch), Ribes spp. (currants), Populus balsamifera ssp. trichocarpa (black cottonwood), Prunus spp. (cherries), and Cornus sericea (red osier dogwood) interrupt the broad expanses of sagebrush scrub.

Juniper zone (1,650-2,000 m).Juniperus occidentalis (western juniper) dominates the vegetation between 1,650 and 2,000 m. Artemisia tridentata ssp. vaseyana (mountain big sagebrush), Festuca idahoensis (Idaho fescue), Achnatherum spp. (need legrasses), and Artemisia arbuscula (low sagebrush), in shallower soils, occupy drier sites in this zone. Cercocarpus ledifolius var. intermontanus (mountain mahogany), Purshia tridentata (bitterbrush), Ribes cereum (wax currant), and Achnatherum lemmonii (Lemmon's needlegrass) predominate in the rimrock areas. Seasonally moist depressions, vernal pools, clay barrens, riparian meadows, seeps, gorge-bottom woodlands and mesic north-facing Populus tremuloides (aspen) dominated slopes all contribute to the habitat diversity in this zone.

Aspen/upper sagebrush/grass zone (2,000-2,400 rn). The "subalpine" elevations of Steens Mountain are a mosaic of aspen stands, sagebrush grasslands, rimrock/talus, and riparian meadows. Populus tremuloides (aspen) stands dominate sheltered and mesic sites between approximately 1,900 and 2,300 m. Symphoricarpos rotundifolius (snowberry) and Ribes spp. (gooseberries) are common shrub codominants; here. The more exposed and xeric sites up to 2,400 m (or higher in some areas) are frequently dominated by Artemisia tridentata ssp. vaseyana (mountain big sagebrush) and a variety of forbs and grasses including Dugaldia hoopesii (orange sneezeweed), Cirsium peckii (Steens thistle), Castilleja spp. (paintbrushes), Lupinus spp. Lupines), Elymus elymoides ssp. californicus (squirreltail), and Poa cusickii (Cusick's bluegrass). Meadows dominated by graminoids such as Carex spp. (sedges) and Poa wheeleri (Wheeler's bluegrass), and perennial forbs such as Antennaria spp. (pussytoes), Potentilla spp. (cinquefoils), Swertia radiata (green gentian), and Penstemon rydbergii (Rydberg's penstemon), are common, as are springs and seeps dominated by Veratrum californicum (false hellebore) or Salix spp. (willows). The striking absence of subalpine conifers is evident in other northern Great Basin ranges, but none as large as Steens. The remarkable absence of subalpine conifers is probably related to Steens' isolation and possibly the biology of such seed dispersers as Clark's nutcracker. Hansen 0 956) speculated that Native American use of fire permanently eradicated conifers that had been present historically, but evidence supporting this hypothesis is scant.

Alpine bunchgrass/tundra zone (>2,400 m). The highest vegetation zone on Steens, above approximately 2,400 m, has been referred to as either subalpine grassland (Mairs 1977, 1979) or true alpine tundra (Collins 1978). Like that of other Great Basin ranges (Major and Taylor 1977), the alpine vegetation of Steens Mountain is developed best in the wetter sites. Within this alpine belt several vegetationally distinct habitats can be recognized. The dry gravelly, windswept summit ridges have a characteristic xeric flora, including Erigeron compositus (cutleaf daisy), Eriogonum umbellatum var. dichrocephalum (sulfurflower buckwheat), Astragalus whitneyi (balloon milkvetch), Geum triflorum (old man's whiskers), Castilleja pilosa var. steenensis (Steens paintbrush), and Arenaria aculeata (prickly sandwort). Dry bunchgrass communities below the ridge crests are dominated by Poa secunda (Sandberg's bluegrass), Festuca spp. (fescues), and Carex spp. (sedges). A complex assortment of alpine wet and mesic meadows occur in cirques and pockets where snow accumulates and provides perennial water in the form of springs and/or a high water table. Polygonum bistortoides (American bistort), Potentilla spp. (cinquefoils), Mimulus spp. (monkeyflowers), Veronica spp. (speedwells), Ranunculus spp. (buttercups), Pedicularis spp. (elephantheads), Carex spp. (sedges), Juncus spp. (rushes), and Agrostis spp. (bentgrasses) are common. Talus and scree slopes, snowbanks, rock outcrops, and riparian Salix spp. (willow) dominated areas are evident on Steens as in other alpine regions.

What Makes a Plant Rare?

A plant may be considered rare for one or a combination of the following reasons: (1) It covers a small geographical range, (2) it has very specific habitat requirements, and (3) it exists in small populations of sparsely distributed individuals. Clearly, a species will be considered rare by anybody's definition if it has few individuals, requires limited and specific symbionts or soils, and is restricted to a small geographical area. Furthermore, if such a species is threatened by any natural or anthropogenic environmental change (mining, recreation, invasion by exotic plants, and so forth), it may be considered in danger of extinction. Conversely, if a plant exists in large populations with a large ecological amplitude, it may not be considered rare even if its geographical range is very small. There are numerous permutations between these two extremes, so deciding whether a species is rare is not often a simple matter.

One of the most interesting types of rarity is based on limited geographical distribution. A taxon is endemic if its distribution is limited to one area. A plant may be endemic to a large area (such as western North America) or to a small area (such as Steens Mountain). A species may be endemic for a variety of reasons that can be considered to span the range between the two extremes of paleoendemic and neoendemic. Paleoendemic s are relictual - remnants of taxa that were once more widespread. Neoendemics are newly formed taxa. that may be in the process of expanding their range from their points of origin.

Rare Plants on Steens Mountain

There are at least six taxa endemic to Steens and nearby ranges, all of which are evidently neoendemics: Agastache cusickii, Castilleja pilosa var. steenensis, Cirsium peckii, Draba cusickii var. cusickii, Penstemon davidsonii var. praeteritus, and Poa chambersii. All Steens Mountain endemics inhabit alpine rock outcrops or gravelly soils. This is an environment that was probably able to retain sufficient moisture during the driest period of the Holocene, though it no doubt experienced extended periods of drought, and thus imposed selective pressures that may have driven speciation.

If we are interested in a plant's rarity because we wish to maintain biological diversity, it matters how genetically diverse rare species' populations are and how genetically differentiated a rare species is from its close relatives. For example, two species with equally small population sizes, habitat requirements, and geographical ranges may not be considered equally "rare" genetically if one represents a small genetic variation (say, a subspecies or variety) from a widely ranging common species and the other represents a large genetic deviation (say, a different genus) from its most closely related species. From this perspective, one would surmise that the endemic plants of Steens Mountain do not provide the genetic diversity contributed by paleoendemic genera (such as Kalmiopsis from the Siskiyou Mountains in southwestern Oregon, or several of the California endemics).

For the past two decades Oregon has been developing a database of rare plants. The Oregon Natural Heritage Program (e.g., ONHP 1998) list is periodically revised, and some taxa once considered rare by criteria of small range or population size may be removed from the list. This is the case for several annuals found on Steens Mountain, such as Dimeresia howellii and Nemacladus rigidus.

Though Steens Mountain is a center of high plant species diversity, none of the vascular plant taxa of Steens is listed as either endangered or threatened at either the federal or state level. Only 2 taxa Castilleja pilosa var. steenensis and Lupinus biddlei) are candidates for consideration, meaning that they require "active protective measures to insure their survival" but that information on their biology and distribution is limited. The Steens paintbrush (C. pilosa var. steenensis) exists in several small populations along the summit ridge from the east Kiger rim to south Steens. Biddle's lupine (L. biddlei) is not a recognized taxon by the most recent treatment of Fabaceae (Barneby 1990). It inhabits sagebrush-dominated sites in the lowlands.

Taxa on ONHP lists 2, 3, and 4 are either (a) endemic but having sufficiently large populations to be considered not threatened with extinction or likely to become threatened under existing conditions (e.g., Agastache cusickii, Draba cusickii var. cusickii, Penstemon davidsonii var. praeteritus); or (b) rare or well-distributed outside of Oregon but having limited population sizes or disjunct populations in Oregon.

Many Steens Mountain species (e.g., Carex haydeniana, C. nova, Cymopterus nivalis, Lloydia serotina, Saxifraga adscendens, Sedum debile, Polemonium viscosum) are widely distributed in the northern Rocky Mountains but are rare in Oregon. Others on Steens that are rare in Oregon are disjuncts from the Sierra Nevada flora (e.g., Allium campanulatum, Claytonia nevadensis, Salix orestera). Fewer Steens plants with affinity to the flora of the Sierra Nevada are listed as rare (by ONHP) than plants with Rocky Mountain affinity, because many taxa common to Steens and the Sierra Nevada are also found throughout the Southern Cascades and thus are not rare in Oregon. Other Steens taxa that are rare in Oregon are at the northern end of their range in the Great Basin and may not be considered rare in Nevada, for example. These are typically low-elevation taxa such as Chaenactis macrantha, C. stevioides, Caulanthus major var. nevadensis, Allenrolfea occidentalis, Phacelia gymnoclada, and Argemone munita ssp. rotundata, but also include a smaller number of taxa in the alpine such as Ivesia baileyi var. beneolens.

Several taxa on Steens are rare in Oregon because populations tend to be very small and sparse and/or the specific habitat required is rare even though the taxa may be more widely distributed in Oregon (e.g., Botrychium lunaria, B. pinnatum, Gentiana prostrata, Gentianella tenella, Kobresia bellardii, Carex backii, C. praeceptorum, Allium madidum, Salix arctica). Each of these has three or fewer known populations on Steens Mountain.

Perhaps the most distinctive plant of the Steens Mountain flora is the Steens Mountain thistle (Cirsium peckii). To the untrained eye, the plant appears to be the common, widespread (but allopatric) bull thistle of lower elevations. Steens Mountain thistle is not considered rare in Oregon, despite its endemism to Steens Mountain, because of its abundance and status in the area. The plant is a ruderal species - it thrives on disturbance in an otherwise moderate habitat. Like a garden weed whose population increases after cultivation, Steens Mountain thistle proliferates along open disturbed roadsides, landslides, and similar sites throughout the montane zone. This is hardly the behavior one expects of a narrow endemic. However, for some reason related to Steens Mountain's isolation and the biology of the plant and/or its symbionts, the Steens Mountain thistle has not yet left the Steens-Pueblo range since its origin, probably in the late Pleistocene or Holocene.

A number of species on Steens Mountain are not considered rare in Oregon but they have limited distributions on Steens and are unusual in some respect that relates to Steens's unique botanical history and geography. For example, in 1992 1 found bog wintergreen (Pyrola asarifolia) in the understory of the willows (Salix planifolia ssp. planifolia and S. orestera) of wet cirque bottoms. This plant is found in coniferous forests and shaded wetlands from California to Alaska and east through Canada. It is a "west slope" plant. The populations on Steens are probably relicts from when cool, moist, closed-canopy wetlands were more continuously distributed from Steens Mountain to the Sierra-Cascade cordillera, possibly via the Wallowa and northern Rocky Mountains. Several other taxa are rare on Steens but more abundant elsewhere in Oregon. Saxifraga rivularis and S. cespitosa are found on wet rimrock cliffs on Steens in only one or a few populations, respectively Similarly, Melica stricta and Pellaea breweri are rock crevice species that are rather rare on Steens but not regionally. Other Steens taxa, such as Alopecurus geniculatus and Plagiobothrys hispidus, are morphologically different from other Oregon specimens of the same species (even when observed in the alternating wet and dry years of the 1990s). In the case of the fir (Abies) on Steens (in small isolated populations in both Fir Creek and Moon Hill), there is disagreement about the genetic affinity of the taxon on Steens. This may be disjunct from the Abies grandis of the northern Rocky Mountains (Flora of North America Editorial Committee 1993) or disjunct from Abies concolor var. lowiana of the Sierra Nevada Mountains (Urban 1981). This is the only conifer on Steens Mountain other than western juniper and common juniper. It provides a good example of a relict population from the moist Pleistocene, but whether it is a relict of populations to the southwest or north remains to be determined.

Other taxa are not on the rare plant list because they are in taxonomically difficult groups that are currently being described or revised. Only one record of the shaggy-leaf willow (Salix glauca var. villosa) is known from Oregon. Having only recently been identified (George Argus, personal communication), this plant from Kiger Gorge on Steens will soon be listed as one of the rarest in Oregon. Similarly, Barbara Etter recently found on the summit ridge of Steens the only population of Potentilla pensylvanica known to occur in Oregon.

In light of the existing disjuncts and endemics, and the isolation of Steens, it would not be surprising to find some genetic differentiation among other species that may be morphologically obscure. At the present time, we know virtually nothing about the genetic variation between plant taxa on Steens Mountain and those of other ranges, and can only base discussions of rarity on the morphological characteristics we see in herbarium specimens. Even as herbarium specimens are examined, we continue to find novelty in the Steens flora. Further systematic studies that include Steens specimens are warranted.

The alpine plants of Steens Mountain most characterize its unique botany. The region above 2,400 in is the smallest of the vegetation zones in terms of area, but it has the largest number of rare taxa. Areas with most rare species are the wet areas - wet and subirrigated meadows and wet gravels by receding snowbanks - and the rock outcrops. The alpine wet meadow species (e.g., the botrychiums, gentians, and graminoids) are alpine disjuncts that were part of a flora shared by other ranges. These habitats on Steens contain several other alpine taxa (e.g., Pedicularis attollens) that are not rare but are disjunct. These wet environments probably lost several species to local (and global?) extinction during the Holocene altithermal period (about 6,000 to 8,000 years ago on Steens Mountain). By monitoring species in these habitats we may have a good biological indicator of the effects of global warming on the northern Great Basin.

At lower elevations, the botanically unique areas tend to be the drier sites, such as ash bed, sandy soils, and clay depressions in the scablands. These habitats have probably also imposed selective pressures that, combined with population fragmentation (due to the patchy nature of these environments), may have forced speciation throughout the Great Basin during the Pleistocene and Holocene, resulting in new, rare taxa.

What are the effects of juniper encroachment (Miller and Rose 1995), grazing, and recreation on the rare flora of Steens Mountain? Few, if any, taxa are imminently threatened by the juniper encroachment that is evident on Steens Mountain. Clearly, if encroachment progresses to the point of monotypic juniper stands, plant diversity is likely to decrease. Thus, from the perspective of maintaining rare plant habitat, a mosaic of diverse communities is desirable, and juniper woodlands should be managed accordingly. Most of the alpine zone taxa are fairly secure with current grazing policies that, when enforced, prevent grazing above 2,400 in (8,000 ft). Many of the alpine meadow taxa may have been more widespread before sheep grazing ravaged Steens earlier this century, but this is conjecture. At lower elevations, however, grazing may be taking a toll on rare plants in riparian areas. For example, at least three low-elevation, riparian taxa (Juncus capillaris, Juncus tiehmii, and Mimulus evanescens) are known from Steens Mountain only by historical records. It is quite possible that the Steens populations may have been decimated as a consequence of habitat destruction associated with grazing. Numerous wetland taxa are known from only one or a few populations on Steens (e.g., Carex backii, Allium madidum, Downingia laeta, D. insignis, Myriophyllum sibiricum, Potamogeton diversifolius, P. filiformis). These are indeed threatened by any activity that will disturb plant population processes, including grazing.

Recreation can impose significant threats to rare plants, but whether recreation threatens rare plants on Steens is largely unstudied. As with grazing in riparian areas, any disturbance to plant population processes can be problematic. Thousands of people now visit Steens annually, however, few travel to the sites inhabited by most rare plants. The Steens paintbrush is perhaps most threatened by recreation because its habitat is one most frequently visited. Because so many of the rare plants exist in only a few populations, it is imperative that all visitors, including botanists, "tread lightly."

What makes Steens Mountain interesting botanically, then, is the unique combination of Rocky Mountain and Sierra alpine and, to a lesser extent, montane plants. As a consequence of the isolation of Steens from these floras, to the northeast and southwest, respectively, some of the taxa have differentiated sufficiently to produce new species or varieties that are endemic to either Steens (e.g., C. pilosa var. steenensis and D. cusickii var. cusickii) or Steens and some combination of the surrounding ranges (e.g., C. peckii and R davidsonii var. praeteritus). Other taxa simply remain as populations disjunct from the rest of their species to the northeast or southwest. Being at the northern limit of the Great Basin physiographic province also means that the Steens and surrounding basins are the only Oregon home to several taxa more common to the south. This is particularly true of the desert flora. Though there are several alpine endemics as a consequence of this unique geographic position, the endemics are all fairly recent in origin, owing to the relatively recent geological history of the area and the fairly radical climate change that the area has experienced during the Quaternary Period.

Brief History of Botanical Exploration

The history of botanical exploration of Steens can be divided into three phases: early exploration, expanding collections and classification, and continuing exploration.

Early explorations of Steens Mountain began in the late 1800s, when a few collections were made by William Cusick, John Leiberg, Thomas Howell, and others. In the early 1900s Morton Peck, Percy Train, Lilla Leach, Louis F. Henderson, and others briefly visited Steens. Of these, Percy Train's collections were the most extensive and unique, providing the only record of several of Steens plant species.

Through the mid-1900s collection trips increased in frequency, mainly from western Oregon, Utah State University, and the New York Botanical Garden by such individuals as Albert Steward, Arthur Cronquist, and Bassett Maguire. Also at this time, several plant systematists; visited Steens to examine unique specimens discovered in earlier collecting forays. Until my recent survey, the most extensive botanical collection was done by Charles Hansen in the early 1950s, as part of his doctoral studies on the vertebrates of Steens Mountain (Hansen 1956).

Today exploration continues through Malheur Field Station (MFS) and the U.S. Bureau of Land Management (BLM). Botany classes at MFS from the mid1970s to mid1980s, led separately by the late Karl Urban and Karl Holte, explored new areas of Steens and continued to contribute to new and unusual records. Collections by Urban, Holte, and their students occasionally provide the sole record of Steens's plant species. From the late 1970s through the early 1990s, the BLM has contracted with botanists to survey various parts of Steens Mountain and the adjacent Alvord and Malheur basins. Since the late 1980s, I have been collecting extensively (independently, with students, through MFS classes, and in cooperation with BLM) to describe the composition, distribution, and variation in the flora and document historical reports lacking vouchers. We now have an adequate sense of the distribution of several species on Steens and in the region and can begin to interpret the origins, relationships, and uniqueness of the Steens Mountain flora. A vouchered checklist of vascular plants on Steens Mountain was recently published (Mansfield 1995).

How to Use the Keys in This Book

A dichotomous key is a standard tool by which biologists identify organisms. It is nothing more than a series of paired questions about the plant you wish to identify. At each couplet (e.g., la and lb) two mutually exclusive alternatives are presented. A tentative decision is made about which of these best applies to the plant in hand. After making a choice, the key instructs you that either you have arrived at the group that includes the organism you are identifying or you are to go on to another couplet.

      1a. Plants woody with a single stem..........................................................Trees.
      1b. Plants either not woody or if woody, then with more than one stem...........2

In many floras the keys are brief and a lengthy description of the characteristics of each species is included. This is the format of the multivolume Intermountain Flora published by the New York Botanical Garden, which covers the larger geographic area including Steens Mountain. In a field guide, such as this Steens Flora, complete descriptions for all species are eliminated and more information is included in each couplet to allow ample opportunity to examine several characteristics that distinguish groups. If information about one characteristic (e.g., the fruit) is not available (e.g., because the plant is in flower and has not yet matured to produce fruits) or is ambiguous, then go on to the next characteristic. Several hints will help nonbotanists use the keys more effectively.

  • Several characteristics are included, separated by semicolons.
  • Read the first half of the couplet to the first semicolon and then the second half of the couplet to the first semicolon, making a choice based on one characteristic.
  • Repeat the process for the next characteristic (from first to second semicolon) and so on, until you have evaluated all characteristics.
  • Trust yourself. It is often easy to convince yourself of the presence of a structural feature but more difficult to convince yourself of its absence. If you do not see a structure it is probably because the structure is not there (assuming you're looking in the right place).
  • Read the couplets carefully. Be sure to assign the qualities to the intended object.

For example:

      7a. Leaflets hairy, over 7 mm long, oblong; fruit round.
      7b. Leaflets hairless, less than 7 mm long, linear; fruit flat.

All adjectives before the first semicolon describe the leaflets. All adjectives after the first semicolon refer to the fruits. Common mistakes in this couplet include measuring the leaves (rather than leaflets), looking for round leaflets (rather than round fruits), or looking for hairs on the fruits, petioles, or stems (rather than on the leaflets).

  • When measurements are given, these refer to height or length of normal, fully developed structures, unless otherwise noted. For example: "Leaves over 7 cm" means "largest leaves are over 7 cm in length".
  • Refer to the figures relevant to the taxa in each choice. Illustrations have been selected to show the important characteristics.

What happens if all characteristics do not result in a consistent decision? Despite care in the writing of each couplet to avoid this possibility, new variations may appear; plants do not read books. The keys are based on examination of existing specimens, which may not include all of the existing variation. Some alpine plants may grow at lower elevations for a couple of years. Some blue flowers may have white mutants in one population. Occasionally a plant growing in an unusually rich site may grow larger than any example ever before seen. (This is especially true for annual plants.) In writing the keys, I have generally used the most stable characters first in the couplets. In some cases, however, the most stable characters are very difficult to use in the field relative to other characters that may be more likely to vary with new finds. Generally, select the most likely option based on all the characters available to you. If you do not arrive at a satisfactory end, return to the place in the key where you had the greatest uncertainty about your choices (not necessarily the beginning).

Though much can be accomplished without magnification, especially if the family is already known, a hand lens is often essential for distinguishing among closely related species in many genera.

The keys were written with the motivated novice in mind. I attempted to keep botanical terminology to a minimum. A few botanical structures are important to recognize before attempting to identify plants, however. These should be reviewed in a basic botany book or an identification guide (e.g., Harris and Harris 1994 or Smith 1977). A glossary and some illustrations are included to facilitate the identification process. An amazing world awaits those with the patience to persist. There are several things you can do to "learn plants":

  • Go out with botanists or others with some knowledge of the local flora.
  • Key (identify) every plant you see!
  • Learn scientific names.
  • When an unusual specimen is encountered, collect it (the entire plant).

How to Make a Plant Collection

A personal herbarium (a "library" of dried plant specimens) can be used to remind you of plants you have keyed and named. Herbaria are maintained to preserve a record of the variation present in our natural environment. They are used extensively in ongoing research about biodiversity, conservation biology, botany, ethnobotany, systematics, and many other fields. In short, without them, we know nothing and have no standards against which we compare what we may find in the future.

Equipment needed:

  1. Digging tool (and sharp knife to cut twigs from trees and shrubs).
  2. Old newspapers (torn along main fold to make single sheets folded once into 12" x 18" folders).
  3. Blotters (about 100 12" x 18"), available at biological suppliers.
  4. Corrugated cardboard (a few more than one for each pair of blotters, 12" x 18").
  5. Two frames of wood either flat or made of lattice, measuring 12" x 18".
  6. Two ropes or straps to tie the press together.

Collect the plant. Plants should be collected with the digger. Collect the entire plant. If a shrub, tree, or unusually large herb is cut, collect part and make a note of the plant size. Collect no more than 5% of the plants in a population. In small populations this may mean taking a photographic record instead of a specimen. Avoid collecting plants that are rare. These are noted in the flora.

Record data on the collection. Information recorded in your notebook will include the following: date of the collections, a number corresponding to the plant you collect, plant size, color of flowers when fresh (they may fade after pressing), fragrances, habitat, elevation, specific location. County, latitude /longitude or township, range, section, and nearby road numbers should be added to the notebook after referring to a map. This step is critical, as many collections are valuable and others may want to return to the location to see the plant you have found.

Press the plant. Remove soil and place the plant into the newspaper folder. Take care to press the plant flat and not folded. Write a number on the newspaper that corresponds to the number in a notebook where information about the plant is recorded. Place the newspaper folder between two blotters, then place the blotter "sandwich" between two cardboard corrugates. Repeat this process with the addition of more plants. After filling the press (10 to 50 iterations), put a wooden frame piece on the top and bottom and tie the press together as tightly as possible.

Dry the plants. Let the press dry in the sun or over a light or oven for several days. Corrugated cardboard between each set of blotters will speed the drying process, but plants will dry even if the cardboard is omitted. Once the plants are dry, they can be stored indefinitely in their newspaper folders or mounted on mounting paper. Plants once pressed in this manner retain the features needed for identification purposes, although colors may fade. Dry plants can easily be reconstituted by placing them in boiling water, so you can save the job of identification until a long winter evening.

Keep plants fresh if they can't be pressed immediately after collection. It is often inconvenient to take a press into the field. Plants can be kept fresh by sealing them in plastic bags. If it will be more than a couple of hours until they will be pressed, it is recommended that they be kept in a cooler. Plants stored refrigerated can often be identified many days after being collected.

Plants dried without being pressed in the manner described above, or plants stored in plastic bags at room temperature, will not be maintained in adequate condition for identification for more than a few hours.

Prepare a label for each plant. A rule of thumb is that the label should contain sufficient information to enable a person to return to the same population at a later date. An example label is shown on the following page.

When rare plants are encountered, they should be reported to the Oregon Natural Heritage Program office in Portland (503-731-3070). Numerous examples of unusual plant collections from Steens in recent years can be cited. Several range extensions have been documented by recent collections. A new species of bluegrass was recently described. In some cases, the form of a particular plant on Steens is very different from the range of variation elsewhere, and botanists have yet to sort out the meaning of these differences. Herbarium collections are essential in this process. Due to the possibility of misidentification, the report of a plant on a checklist does not mean the plant is present. Only a properly prepared collection that can be verified can document a plant's presence.

Harold M. Tucker Herbarium
College of Idaho (CIC)
Cirsium peckii L. F. Henderson     AST
HARNEY CO., OREGON. In disturbed soils along North Steens Loop Road 12.0 miles southeast of Page Springs. Dugaldia hoopesii and mountain big sagebrush dominants. Flowers purple. T33S R33E Sec 5 NE 1/4 2,000 m
20 July 1990     Don Mansfield 2021

Scientific Names

Names are a concise way of describing objects. The scientific name of each species is a binomial that is, it is a two-part name comprising the genus and the species. For example, the scientific name for big sagebrush is Artemisia tridentata Nutt. Artemisia is the genus name for several sagebrushes, sageworts, and wormwoods. The term tridentata is the Latin adjective meaning "three-toothed," because big sagebrushes, but not all other sagebrushes, have leaves with three teeth at the tip. This term, the species epithet, is unique for this species within this genus. We need only recall the similarities (in name and leaf form) between big sagebrush and bitterbrush (Purshia tridentata) to see the importance of the binomial. The same adjective may be used as a descriptor in many different genera. After the scientific name we typically give the standard abbreviated name of the authority (the person who first recognized and named this group of plants), in this case, Thomas Nuttall, a Harvard professor and a botanical explorer of the western United States. Note that the binomial for big sagebrush can be abbreviated A. tridentata when we already know that we are talking about the genus Artemisia.

We are all familiar with this binomial style from our childhood. Most readers of this book will have a surname and a given name. The surname is a more general name shared with parents, siblings, and certain other blood relatives, while the given name is more specific, allowing you to be distinguished from others in your family. And you are often unrelated to those with whom you share a given name.

Unlike people's names, however, species names are given to populations of biological organisms, not individuals. And biological organisms vary considerably because of genetic variation. As a result, the task of the taxonomist is to try to understand genetic relationships and have a useful classification and naming system that reflects relatedness in a meaningful, hierarchical way. Thus, every species should be most closely related to the other species within its own genus. Similarly, different genera within one family should be more closely related to one another than to genera of any different family, and so forth. As botanists gain further knowledge of the plants in our region, new interpretations emerge about genetic relationships between our taxa and those from around the world. Several effects of such studies may be observed in a field guide such as this.

Scientific names encountered in this book may differ from names you encounter in older literature for the same plants (i.e., plants of the same populations). Most commonly, species are reorganized into different genera. Usually this results when a taxonomist splits a genus (e.g., Potentilla, Gentiana, or Haplopappus) that had served for decades as a catchall for any and every species that had a particular suite of morphological characteristics, whether those characteristics reflected their genetic relatedness or not. Often cytological, genetic, molecular, or other biosysternatic study reveals distinct subsets that align more with a concept of "genus" than of "section" within a genus. Often studies will locate taxa from Eurasia that may be more closely related to a particular North American species, and both must be included within the genus name that was published first, according to the rules of the International Code of Botanical Nomenclature. In either case, different genus concepts largely reflect the opinions of botanists that fall somewhere between the extremes of "lumper" and "splitter." Perhaps the most frustrating kinds of changes are those in which taxa are lumped from two or more different genera (e.g., Castilleja and Orthocarpus, or Epilobium and Bouisduvalia) or completely recombined among several genera (e.g., Elymus, Sitanion, Agropyron). The new arrangement requires that different morphological characteristics must be learned to recognize the newly combined genera in the field. This is nothing new to taxonomy. Every new generation learns a slight modification of their predecessors' categories.

Sometimes, species names change for reasons similar to those for which genera are combined or split. For example, Poa secunda Presl will be seen here to include what was previously called P. ampla Merr., P. juncifolia Scribn., P. nevadensis Scribn., R sandbergii Vasey, Poa canbyi (Scribn.) Howell, R scabrella (Thurb.) Benth., and R incurva Scribn. & Williams. Sometimes different authors have different concepts of species. For example, the same plant on Steens that will key here to Potentilla versicolor Rydb. will be called P. millefolium in the Intermountain Flora (Cronquist et al. 1997) and P. ovina Macoun in the Flora of the Pacific Northwest (Hitchcock and Cronquist 1969). Disagreement may result from different interpretations of the relative importance of biogeography, ecology, morphology, or genetics in defining a species, or it may also result from insufficient number of specimens to study to form justifiable interpretations of any sort. In other cases, species names may change because of priority issues. For example, Koeleria macrantha (Ledeb.) Schult. was called K. cristata Pers. until it was realized that the K. macrantha had been described in an earlier publication for plants whose populations are most similar to ours. Similarly, misinterpretations are continuously being discovered. For example, spotted knapweed in our area has been called Centaurea maculosa until in 1999 a German graduate student recognized its origin as C. stoebe L. ssp. micranthos.

Recent, but not all, synonyms (older names used to describe the same populations of plants) are included in this book and indexed to help avoid confusion.

All of these changes simply illustrate two phenomena about taxonomy. First, the legacy of evolutionary history represented in each plant population is unique, and no single rule for defining a "genus" or "species" will apply in all cases; some are large and others small, some are clear and others ambiguous, for reasons that have to do with each group's unique heritage. Second, the process of unraveling this legacy is ongoing. The expectation that our taxonomic categories are fixed pigeonholes will be unfulfilled.

Common names are used throughout this book, though in most cases are no easier or more helpful than the scientific names. With knowledge of the scientific names the reader has much greater access to a wealth of information about these marvelous creatures that may be missed entirely if familiar only with the common name.

While it may frustrate a reader familiar with several scientific names that some of those scientific names have changed recently, it will likely be even more frustrating how common names change. The most useful common names emerge from descriptions of the plants by those who have used them for foods, medicines, and so forth. Native American names such as yampa (for Perideridia), chucklusa (for Lomatium canbyi), and kinnikinnik (for Arctostaphylos uva-ursi) are both useful and worth preserving for their cultural value. There are, however, some limitations of common names. Kinnikinnik, for instance, refers to any plant used as a pipe tobacco, so the name applies to many different species in different regions. In Canada kinnikinnik refers to Amelanchier, which we in the U.S. call serviceberry. Furthermore, the same plant species may have different common names in different areas. For example, Arctostaphylos uva-ursi is called each of the following in different areas: mountain box, barren-myrtle, rapper-dandies, universe-vine, and hog-crawberry, So while the vernacular may be easy in some respects, it may be very confusing, especially if traveling to other areas.

Fortunately, many plants retain their Latin name as their common name, as is the case with Asparagus, Chrysanthemum, and many others. In this book I have not made an effort to preserve the diversity of common names that may exist for a particular plant. I have used those which I believe to be most preferred in our area. I have, however, provided a common name for every species. In some cases these are merely Anglicized translations of the Greek or Latin root. In such cases, I strongly discourage use of any common name.

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