Taraxacum

Lacking a treatment putting our introduced North American taxa into the context of the hundreds of microspecies named from Europe, we recognize three broad collective species here, as done in essentially all North America floras, that are best viewed as equivalent to the sections Erythrosperma, Palustria, and Taraxacum of European works. Going further would require a dedicated collecting program, since much existing herbarium material is inadequate for recognition of microspecies. A number of specimens here referred to T. erythrospemum were identified in 1985 by Reinhard Doll, a European specialist in Taraxacum, as T. scanicum Dahlst., a common microspecies in dry, especially sandy, places in Europe. Also noted were T. disseminatum G. E. Haglund and T. aff. fulvum Raunk. Our plants called T. palustre are apparently referable to the microspecies T. cognatum Štĕpánek & Kirschner.

A native species of Taraxacum, presumably T. ceratophorum (Ledeb.) DC. s. l., is known from cliffs on the Ontario side of Lake Superior and could be found in northernmost Michigan. It has the phyllaries much more conspicuously appendaged than our alien species and also leaves less lobed than our common species.

1. Outer phyllaries straight, dark gray to nearly black; leaves merely toothed or shallowly lobed, usually less than 2 cm broad.

T. palustre

1. Outer phyllaries recurved, usually green to purple or brown tinged; leaves deeply lobed to ± entire, often more than 2 cm broad, especially if ± entire.

2. Body of achene red-brown, ca. 2.5–3 mm long, usually spiny from apex to middle or below; leaves deeply pinnatifid, cut nearly to midrib; phyllaries (some, not all) often with a small protuberance just below the apex.

T. erythrospermum

2. Body of achene gray to yellow-green or pale brown, ca. 3–3.5 (–3.7) mm long, spiny above the middle; leaves various (from deeply pinnatifid to nearly entire); phyllaries without a protuberance.

T. officinale

All species found in Taraxacum

Taraxacum erythrospermumRED-SEEDED DANDELION 
Taraxacum officinaleCOMMON DANDELION 
Taraxacum palustreMARSH DANDELION 

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. August 18, 2017. http://michiganflora.net/genus.aspx?id=Taraxacum.