First Blooms of the Oregon Flora Project 
The Oregon Vascular Plant Checklist: Asteraceae 
Kenton L. Chambers and Scott Sundberg 
Herbarium, Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331 
I n June of 1998, the Oregon Flora Project issued, as its first 
publication, a formal list of the accepted names of all the 
composites (family Asteraceae) known from Oregon. The 
list was reprinted in May 2000, with changes and additions. 
Written by Project members Kenton Chambers and Scott 
Sundberg, this 56-page booklet includes all the taxa (genera, spe¬ 
cies, subspecies, and varieties), both native and naturalized, com¬ 
prising Oregon's largest family of flowering plants. The list is the 
first installment of the Oregon Vascular Plant Checklist, which 
will be published as a series of fascicles treating all Oregon vasr 
cular plant families and culminating finally in a one-volume, 
comprehensive list. The first draft was compiled in 1989 by Karl 
Urban, with assistance from Kenton Chambers, and was based 
mainly on the published floras and taxonomic literature avail¬ 
able at that time. Since then, members of the Oregon Flora Project 
and dozens of invited specialists have been revising the list, fam¬ 
ily by family. In addition, there is a Checklist Advisory Board of 
nine members, who are asked to review all the treatments of 
plant families submitted by these authors. 
The Checklist is maintained in a Paradox computerized da¬ 
tabase at the Oregon State University Herbarium. The data are 
periodically updated, and the statistics cited below are derived 
from the January 2001 version of the database. A digital version 
of the Asteraceae checklist can now be viewed online by visiting 
the Oregon Flora Project website at http:/Avww.oregonflora.org. 
This version will continue to be updated as new information 
becomes available. 
Production of the Checklist is a fundamental step toward 
writing a new Flora of Oregon. Our goal is to determine which 
plants occur in the state and to make critical decisions on what 
names should be used for them. In some ways, the writing of a 
checklist is the most challenging step, as it requires reviewing all 
available literature and examining thousands of herbarium speci¬ 
mens. The Checklist has a further purpose, which is to spur in¬ 
terest in Oregon plants and to encourage users to report new or 
unusual plant records. In this article we provide a brief summary 
of the Asteraceae list, show the process used to prepare it, and 
discuss our approach in the context of earlier floras. 
The Asteraceae checklist includes accepted names of all 
Oregon taxa growing outside of cultivation, their common names, 
origins (native or exotic) and comments on taxonomic problems 
and hybridization (see Guide for Contributors in the Oregon 
Flora Project website). All included taxa have been verified 
through at least one voucher specimen in the three herbaria 
housed at Oregon State University. Only in rare cases, when no 
voucher collection is present in our herbaria, will a published 
reference to specimens in other herbaria be cited. Because vari¬ 
ous books may differ in the naming of certain Oregon plants, 
each accepted name in the Checklist is followed by all the alter¬ 
native scientific names that appear in ten standard floras and 
lists of Oregon species. Excluded species, those whose presence 
in the state has not been confirmed, are listed in an appendix. 
The Asteraceae, or Compositae, is one of the largest, most 
rapidly evolving, and most successful families of flowering plants. 
It has the largest number of species of all the families in Oregon's 
flora. Some Oregon Asteraceae are dominant members of their 
communities, for example sagebrush and rabbitbrush, which are 
familiar components of arid landscapes east of the Cascade Moun¬ 
tains. The Asteraceae also contains some of our worst non-native 
weeds, including dandelion, starthistle, Canada thistle, tansy 
ragwort, and several species of knapweed. A surprising 22 per¬ 
cent of composites in Oregon are non-native species. As pub¬ 
lished in 1998, the Checklist comprised 571 taxa, including 122 
genera and 490 species. Since then, new state records and newly 
published taxonomic research have raised these numbers to 577 
taxa, found in 129 genera and 496 species. There are 108 species 
that include one or more subspecies or varieties. In addition, 
578 synonyms (alternative names) are listed. At present, 41 taxa 
are known from only one collection at Oregon State University, 
which houses the herbaria of this university (OSC), the Univer¬ 
sity of Oregon (ORE), and Willamette University (WILLU). Four 
taxa are known only from old collections on ship ballast in the 
Portland area. Genera with the greatest numbers of taxa are Eri- 
geron (daisies and fleabanes; 49 taxa). Aster (asters; 33), Artemi¬ 
sia (sagebrushes and mugworts; 31), Senecio (groundsels and 
butterweeds; 28), Cirsium (thistles; 20), and Antennaria (pussy- 
toes and everlastings; 19). 
As we worked through the Asteraceae family, species by spe¬ 
cies, our principal task was to choose among the various names 
that are published in standard floras, monographs, and plant 
lists for Oregon. In technical terms, we say that "alternative treat¬ 
ments" have been written by two or more botanical authors. 
Each treatment represents the considered opinion of a particular 
taxonomist—someone who has written a flora of Oregon or has 
published a detailed study of a tribe or genus within the family. 
What one finds in practice is that considerable differences of 
opinion often exist among such authors. Many plant genera, 
especially in a complex family like the Asteraceae, exhibit a high 
degree of evolutionary flexibility and therefore show^ elaborate 
patterns of intergrading variation combined with subtle, minor 
morphological differences between taxa. In many genera, the 
distinctions between species are ambiguous, and there may be 
no consensus among specialists as to what the "best" taxonomic 
approach should be. One expert may view a genus as containing 
a small number of large, variable species (perhaps divided into 
numerous subspecies or varieties), while another may raise these 
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Kalmiopsis Volume 7, 2001 
