Paper pub. date
January 2001
ISBN 9780870714900 (paperback)
6 x 9 inches, 512 pages. Line drawings. Glossary. Index.

Handbook of Northwestern Plants Revised Edition

La Rea J. Dennis and Helen M. Gilkey

The Handbook of Northwestern Plantshas long been one of the most respected and widely used guides for identifying the plants of western Washington and Oregon. Earlier editions of this book have been used by thousands of botany students and other interested individuals to identify hundreds of different species of plants, while learning how to use analytical plant keys and the basic botanical terminology necessary to understand and accurately identify plants in the field.

Intended for use by teachers, students, scientists, amateur botanists, and outdoor enthusiasts, the Handbook of Northwestern Plants brings together in one comprehensive but convenient volume the information necessary to identify the amazing variety of plants found between the Cascade mountains and Pacific Coast in Washington and Oregon as far south as the Umpqua divide. The glossary of botanical terms, illustrations of different types of leaves and flowers, and hundreds of line drawings that highlight the identifying features of various plants will be especially valuable to students and beginners.

To make this new edition as accurate and up-to-date as possible, author La Rea J. Dennis has updated the nomenclature to conform to the latest scientific literature, added species, and revised some plant descriptions and keys. To make the book easier to use, the genera and species have bee arranged alphabetically within families, and the longer keys have been numbered. As in earlier editions, hundreds of excellent line drawings illustrate the key characteristics of various plants.

About the author

La Rea J. Dennis has been studying Pacific northwest plants for more than 40 years. She is retired Assistant Curator of the Herbarium at Oregon State University and the co-author of Plants of the Oregon Coastal Dunes (OSU Press), among other publications.

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Helen M. Gilkey (1886-1972) was a vascular plant taxonomist, mycologist, botanical illustrator and author of numerous publications. She was curator of the herbarium at Oregon State from 1918 to 1951; following her retirement she continued to do research until her death.

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Leaves and Flowers


Analytical Key

Ferns and Fern Allies






This book is intended for botany students and individuals willing to learn to use keys and basic botanical scientific terminology. It is the outgrowth of A Spring Flora of Northwestern Oregon; published in 1929 by Dr. Helen M. Gilkey for use in Field Botany courses. In 1947 she expanded the work so that it would be of use your round to a wider audience. It was published as Handbook of Northwest Flowering Plants; a name change made necessary when the ferns and fern allies were added. Sadly, Dr. Gilkey died in 1972. I revised the nomenclature in the Handbook in 1973 and 1980. In 1999, when the 1980 edition went out of print, and many nomenclatural changes were necessary, Warren Slesinger of the OSU Press persuaded me to do this present revision.

I have updated the nomenclature to conform to current taxonomic literature to the best of my ability, revised some of the descriptions and keys, numbered all but the shortest keys, added a few species, and arranged the genera and species in alphabetical order within the families. Distributional information of species and synonymy have been kept at a minimum in order to keep the book a reasonable size. Line drawings were chosen over photographs because they allow for the illustration of key characters.

Area Covered

The area covered in this book is roughly that of the rather natural floristic unit from the summit of the Cascade Range to the coastline of Washington and of Oregon as far south as the Umpqua Divide, about the southern limit of Lane County, Oregon. Northern Washington, in its more unique botanical aspects, has been excluded.

Plant Classification and Nomenclature

The development of botany as a science was coincident, in its beginning, with that of medicine. Plants were early employed as remedies for various ills. As a knowledge of disease and its cure grew more specific, it was natural that some attempt at classification of the plants employed by made. From the beginning of human existence, plants and animals have been given common names which are useful locally. The difficulty lies in the fact that these names are purely local. A widespread plant such as Hypericum perforatum L. will have several common names; in Oregon alone it is know as Klamath Weed, Goat Weed, and Common St. John's wort; to the Chinese it is Chin Ssu T'ao Shu; to the Germans, Johanniskraut and to the French, Millepertuis perfore. yet botanists throughout the world would immediately recognize the name Hypericum perforatum L. Also the same common name is often applied to different plants in different parts of the country, and there are many plants without common names. Obviously a system need to be devised. Consequently, International Botanical Congresses have met at regular intervals since 1867 for the purpose, in part, of establishing and stabilizing botanical nomenclature (a system of naming plants) on an international basis. In order to maintain the integrity of the system, the rules are published following the convening of each congress under the title International Code of Botanical Nomenclature. As a beginning, for the purpose of uniformity, Latin was adopted as the official language, and each plant was to be assigned a name consisting of a binomial, i.e., two associated words. The first word is the genus (or generic name); the second, the species (or specific epithet). Technically these are followed by the name of the person who bestowed the specific epithet. Thus, our common Red-flowering currant is known as Ribes sanguineum Pursh (genus, Ribes , species, sanguineum , and Pursh for Frederick Pursh, who first described the species).

In earlier editions of the handbook, Ribes was in the family Saxifragacea, in this edition it is in a segregate family, the Grossulariaceae. It must be noted that while definite International rules govern the naming of plants and must be followed, in certain cases an author is free to choose between two names. This choice involves the question of splitting a previously named family into several separate families and authors are free to use their own judgement. While I have always been considered a "lumper" and not a "splitter," I felt in this case it was reasonable to remove the woody genera from the Saxifragacea. Similar situations may occur in the treatment of genera, which explains why Oregon grape may be listed correctly under either Berberis or Mahonia.

Taxonomists are often criticized for continually changing the names of plants. It must be remembered that, in spite of the antiquity of the science, new information is continually being accumulated and earlier classifications must be revised. Also the plants involved are living, dynamic, and often fluctuating populations and, as such, are not always interpreted in exactly the same manner by all taxonomists. It is necessary to keep the names as stable as possible while allowing for a difference of opinion among specialists.


Identification of unknown plants are usually made by means of keys. Keys present the user with a progressive sequence of choices, and, by always making the correct choice, one will arrive at the name of the unknown plant. Normally the first step is to determine the family to which the plant belongs by suing the family key. If the family is already known, or when one has arrived at a family in the key, the description of the family should be read to determine if the plant could belong there. If a mistake has been made, it will usually show up at this point. If the family appears to be correct, then the key provided should be used to determine the genus and, following the genus description, the key to species. Upon arriving at a species name, the species description should be read carefully and compared with the plant in question.

The following points should be kept in mind when using a key:

  1. Read both choices given, for although the first choice may sound good, the second choice is sometimes better.
  2. Be certain that the terminology is understood; look up any term about which you are uncertain.
  3. When measurements are required, make them accurately.

Selected References

of special value in our area: Vascular Plants of the Pacific Northwest,

Hitchcock, C.L., A. Cronquist, M. Ownbey, and J.W. Thompson. 5 vols 1955, 1959, 1961, 1964, 1969. University of Washington Press, Seattle, WA. The Jepson Manual: Higher Plants of California,

Hickman, J.C., editor. 1993. University of California Press, Berkeley, CA. Flora of North America North of Mexico.,

Flora North America Editorial Committee, eds. 1993+. Oxford University Press, New York, NY. When completed the flora will consist of 30 vols. Also still useful, but out of print, is: A Manual of the Higher Plants of Oregon,

Peck, M.E. 1961. Binfords and Mort, publishers, Portland, OR. There are other more local floras which are very good for the areas they cover, for example: Wildflowers of the Western Cascades,

Ross, Robert and Henrietta Chambers. 1988, Timber Press, Portland, OR. Flora of Mount Rainier National Park,

Biek, D. 1999. Oregon State University Press, Corvallis, OR Wildflowers of the Columbia Gorge,

Jolley, Russ. 1988. Oregon Historical Society Press, Portland, OR.


I cannot adequately express my gratitude to Richard R. Halse and Robert F. Obermire for reviewing the entire manuscript and helping with the proof reading. their suggestions have undoubtedly made this book more useful. I am also indebted to The Oregon Flora Project and to George Arus, Henrietta L. Chambers, Kenton L. Chambers, Rhoda Love, and Scott Sundberg, who gave freely of their time and expertise. I would like to express my appreciation to Elizabeth Waldron, Lynda M. Ciuffetti, Dianne L. Simpson, and Typhanmi Johnston, who have been a constant source of encouragement to me. I would be remiss if I did not thank my many other friends, too numerous to name (for I fear I would inadvertently omit one), who encouraged me and sometimes distracted me from my work on this revision. Thanks are also due to the staff of the OSU Press, especially: Jeffrey Grass, Warren Slesinger, Jo Alexander, Mary Braun, Tom Booth, and Pennie Coe. I would like to take this opportunity to thank my many students who over the years have made suggestions for improvements in keys and descriptions. Yes, I was listening to you and I did keep notes and I have tried to incorporate many of those suggestions into this edition. Thanks are still due all those persons who assisted in preparation of the earlier editions: Maxwell K. Phinney, James R. Estes, Beulah G. Gilkey, Weldon K. Johnston, Harry K. Phinney, Garland Powell, Frank H. Smith, Ronald Tyrl and to the artists: Cathrine Davis Young Feikert, Daisy R. Overlander, Alleda Burlage, Fern Duncan, and Patricia Packard, who in addition to Helen Gilkey produced the line drawings.

La Rea J. Dennis
May 2000

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