Taraxacum F.H.Wigg.
Perennial, or rarely biennial, taprooted herbs. Hairs eglandular, usually cobwebby, or 0. Stems scapose. Lvs all basal, usually runcinate-pinnatifid, rarely not lobed. Capitula solitary. Involucral bracts glabrous or ciliate; outer bracts < inner, erect to reflexed; inner bracts in ± 1 series. Receptacle colliculate or alveolate, glabrous; scales 0. Corolla ligulate, pale to golden yellow, often striped with grey, red or violet. Style branches filiform, yellow, or green to blackish at least when dry. Achenes numerous, usually pale to dark or reddish brown, sometimes greenish, grey, reddish or purplish, ribbed, scabrid to muricate on ribs, beaked, with a short tapering or cylindric cone at base of beak, rarely cone and beak 0; pappus bristles in many rows, white to sordid, usually > achene body, simple, connate at base.
Key
c. 150 spp. groups (> 1200 microspp.), pantemperate and arctic. Native sp. 1., naturalised 1.
Taraxacum poses taxonomic problems because of its tendency to form myriad apomictic races, the variability of the sexual spp., and the extreme plasticity and seasonal variation encountered. In many countries the apomictic races are treated as spp. (microspp.) even though it is often necessary for their identification to have material collected in spring and preferably not from mown, grazed, trampled, or shaded sites, all habitats frequented by dandelions.
Achenes of Taraxacum nearly always have a short, tapering appendage at the apex of the body, to which the slender beak is attached. This appendage, the cone, is often important in identification. Its pattern of variation within T. magellanicum suggests the presence of several entities within that complex.