The genus
Taraxacum has received widely varying treatments in North America. This is not unexpected in a group of plants in which hybridization, polyploidy, and apomixis are active. Some taxonomists (e.g., Ferris 1960, Weber 1967, Welsh 1974, Tayl. and MacBryde 1977, Douglas et al. 1989, Richards 1994, Cody 1996) recognize six or fewer native species (e.g.,
T. californium Munz. & Johnston,
T. ceratophorum, T. eriophorum, T. lyratum, T. phymatocarpum and
T. spectabile Dahlst.). Others have recognized 10 or more species (e.g., Fernald 1950, Hulten 1968, Scoggan 1979, Porsild and Cody 1980). The most conservative approach for our British Columbia species was taken by Boivin (1966-1967, 1972), Hulten (1968), Packer (1983) and Douglas (1989) who included
T. eriophorum and
T. lyratum within
T. ceratophorum. Hulten (1968), however, included 45 "microspecies" under
T. ceratophorum and still recognized nine other northern
Taraxacum. I have recognized only one native
Taraxacum species in British Columbia for several reasons. Of all the specimens I examined, only a small number would fit the description of the few species generally recognized. The remainder, when mature, represent an amazing array of variation that is often not repeated between sheets. In addition, most of the subalpine-alpine plants never set seed before the end of the short growing season, thus a key character, the achene, is often unavailable for determination. The time spent by several energetic Scandinavian taxonomists (e.g., G.A.H. Dahlstede, G. Haglund, and A.E. Porsild), formally naming several hundred "microspecies", has not enlightened the taxonomy of the genus. Even in recent years some taxonomists persist in naming every variation they encounter (e.g., Richards 1970). Until some brave taxonomist undertakes and successfully completes a thorough modern biosystematic study it would appear that the recognition of more than a single entity is not feasible.
The following identification key may be used to separate our species:
1. Native, non-aggressive, high elevation species (except rarely along roads in extreme northern British Columbia)..................T. ceratophorum
1. Introduced, aggressive weedy species of disturbed sites.
2. Achenes red to reddish-brown or reddish-purple at maturity, the beak mostly 1-2 (sometimes 3) times as long as the body; leaves mostly deeply cut for their entire length, without an enlarged terminal segment, the lobes narrow; outer involucral bracts appressed to loose or sometimes reflexed; inner involucral bracts usually horned at the tips............................T. laevigatum
2. Achenes olive- or straw-coloured to brown at maturity, the beak mostly 2.5-4 times as long as the body; leaves usually less deeply cut, often with an enlarged terminal lobe; outer involucral bracts reflexed, inner involucral bracts not horned at the tips...........................T. officinale
Source: Illustrated Flora of British Columbia
