Antennaria rosea ,rosy pussy-toes (photo copyright S. Sharnoff). 
could validate, to our own satisfaction, the status of Oregon taxa. 
That is, if a species had been reported to occur in the state, we 
tried to verify this from herbarium specimens and, additionally, 
to check that our specimens confirmed the morphological dif¬ 
ferences and variation patterns implied by treatments in floras 
and monographs. In effect, we wanted to learn if the published 
keys and descriptions “worked” in Oregon, and if not, should 
we then modify the taxonomy as it applies to this state’s flora? 
A further important question was whether particular taxa 
should be considered as native to the state, or as “exotic” in ori¬ 
gin—which is generally taken to mean introduced into the flora 
since the advent of European explorers and settlers. The choice 
of native versus exotic can be difficult for species that are native 
elsewhere in North America and in Oregon are found mainly in 
human-disturbed habitats (one might call these species “weeds 
of North American origin”). Some examples are annual sunflower 
(I lelianthus annuus), horseweed {Conyya canadensis), and cock- 
lebur Qianthium strumarium). Many species, including exotics, 
are known only from one or two herbarium specimens, and in 
the Checklist we state where and when these vouchers were col¬ 
lected. Some of these species may no longer exist in Oregon, 
while others may be more common here than the paucity of 
collections would indicate. Examples include orange hawkweed 
(Hieracium aurantiacum), corn marigold ( Chrysanthemum 
segetum), and California false sunflower (I ielianthella californica). 
We hope that by calling attention to these rarely seen species, 
users of the Checklist may be stimulated to report their discover¬ 
ies of novel weeds, escaped garden plants, and unusual occur¬ 
rences of various uncommon native species. 
Probably the most drastic—one might even say upsetting— 
taxonomic changes in the Checklist involve the modification or 
elimination of well-known generic names. A conspicuous ex¬ 
ample of this would be the six new genera to which the Oregon 
species of Haplopappus are now assigned: Columhiadoria, 
Ericameria, Hayardia, Pyrrocoma, Stenotus, and Tonestus. Further¬ 
more, Chrysothamnus, or rabbitbrush, has been dropped, its spe¬ 
cies merged into the genus Ericameria [although some members 
may be returned to Chrysothamnus pending analysis of recent 
research]. A marked increase in computer-assisted phylogenetic 
studies in Asteraceae has led to numerous recent proposals to 
split various large genera and invent new names for the resulting 
segregate taxa. Such proposals tend to be very controversial, both 
because the morphological distinctions between the “new” gen¬ 
era are often quite minor, and because the previously existing 
generic names are well known and widely used. An example of 
such extensive splitting is the proposal to assign the North Ameri¬ 
can species of Aster to at least eight segregate genera—effectively 
removing the familiar name Aster from our native flora! The 
equally well-known butterweed genus Senecio has been similarly 
fragmented. Although these generic splits were not accepted in 
the 1998 Checklist, we are currently reconsidering these nomen- 
clatural changes. 
For the Oregon Checklist we have evaluated various taxo¬ 
nomic changes on their own merits but have tended to be con¬ 
servative in the extent to which we accept new generic names 
and concepts. Many of the changes that do appear in our Check¬ 
list are also to be found in The Jepson Manual, giving a degree of 
consistency to the floristic treatments for Oregon and Califor¬ 
nia. Some examples are our use of the genera Acroptilon, Ageratina, 
Ancistrocarphus, Cacaliopsis, Hesperevax, Heterotheca, 
Eeucanthemum, Nothocalais, Sphaeromeria, and Uropappus, as well 
as the genera segregated from Haplopappus mentioned above. 
Following publication of the Checklist s. 1998, we have evalu¬ 
ated and accepted some further generic realignments from pub¬ 
lished studies at the University of California, Berkeley, based on 
the molecular phylogenetic research of Bruce G. Baldwin and 
co-workers. An example is the placement of spiny skeletonweed, 
formerly known as Stephanomeria spinosa (and even earlier as 
Lygodesmia spinosa) in the unique genus Pleiacanthus, as P. spinosus 
(Nutt.) Rydb. This species was shown, by DNA analysis, to be 
well separated genetically from both Lygodesmia and 
Stephanomeria. Related research on the genera of subtribe 
Madiinae (tarweeds) has led Baldwin to propose dividing the 
genus Madia into several phylogenetically separate lineages. Or¬ 
egon species affected by these changes include M. holanderi [now 
named Kyhosia holanderi (A. Gray) B. G. Baldwin], M. madioides 
[now Anisocarpus madioides Nutt.], and M. minima [which we 
now call Hemiyonella minima (A. Gray) A. Gray]. Such changes 
become necessary when thorough and well-grounded taxonomic 
research leads to a radically new understanding of plant species 
relationships. 
Subspecies and varieties also represent a level in the taxo¬ 
nomic hierarchy where divergent opinions exist among botanists. 
Some authors use the subspecies rank exclusively, others use only 
the varietal rank, and still others make a subtle distinction 
10 
Kalmiopsis Volume 7,2001 
