Taraxacum officinale
Taraxacum trigonolobum
common dandelion, dandelion, pissenlit officinal, red seed dandelion
1–10+, erect or ascending, sometimes ± purplish (usually equaling or surpassing leaves), glabrous or sparsely villous, slightly more so distally.
1–5, ascending to erect, purplish, glabrous or glabrescent proximally, ± densely villous distally.
20+, horizontal to erect;
petioles ± narrowly winged;
blades oblanceolate, oblong, or obovate (often runcinate), (4–)5–45 × (0.7–)1–10 cm, bases attenuate to narrowly cuneate, margins usually shallowly to deeply lobed to lacerate or toothed, lobes retrorse, broadly to narrowly triangular to nearly lanceolate, acute to long-acuminate, terminals ± as large as distal laterals, ultimate margins toothed or entire (secondary lobules irregular, perpendicular to retrorse), teeth minute to pronounced apices acute to acuminate or obtuse, faces glabrous or sparsely villous (commonly on midveins).
fewer than 10, horizontal or patent to ± erect;
petioles widely winged;
blades oblanceolate-obovate (largest in distal 1/5) to oblanceolate (often runcinate, particularly early leaves), (3.5–)6–29.5 × (1.3–)2.1–5.5 cm, bases cuneate to attenuate, margins sometimes lobed proximally or ± regularly and deeply, usually ± strongly toothed proximally (less so on distal 1/2–1/5), lobes retrorse to straight or antrorse, triangular to deltate, ± acuminate, teeth mostly proximal, rarely on distal 1/4–1/5 or terminal lobes, small to coarse, irregular (1–5 on lobes), apices rounded or truncate to obtuse, rarely acute, apiculate, faces glabrous or glabrate (very sparsely pilose, mainly on midveins).
green to dark green or brownish green, tips dark gray or purplish, campanulate, 14–25 mm.
dark green, ± glaucous, broadly campanulate, 15–20 mm.
40–100+;
corollas yellow (orange-yellow), 15–22 × 1.7–2 mm (outer).
120–150;
corollas yellow, outer grayish-purplish striped abaxially, 19–25 × 1.3–2.3 mm.
13–18 in 2 series, lanceolate, 2–2.8 mm wide, margins scarious (proximal 2/3) to narrowly scarious, apices acuminate, erose-scarious, usually hornless (seldom appendaged), callous.
14–20 in 2 series, lanceolate, 2.1–2.8 mm wide, margins ± narrowly scarious (wider proximally, or not in outer series), apices strongly horned, tips purplish with dark center, scarious, ± erose.
of 12–18, reflexed, sometimes ± glaucous, lanceolate bractlets in 2 series, 6–12 × 2.8–3.5 mm, margins very narrowly white-scarious, sometimes villous-ciliate distally, apices acuminate, hornless.
14–20, appressed (to spreading), often pale green, ovate to elliptic-ovate bractlets in 2–3 series, 5–8 × 2.8–4.5 mm, margins narrowly white, scarious (occasionally outer ± ciliate), apices acuminate to caudate, some strongly horned, tips dark-scarious.
olivaceous or olive-brown, or straw-colored to grayish, bodies oblanceoloid, (2–)2.5–2.8(–4) mm, cones shortly terete, 0.5–0.9 mm, beaks slender, 7–9 mm, ribs 4–12, sharp, faces proximally smooth to ± tuberculate, muricate in distal 1/3;
pappi white to sordid, 5–6(–8) mm.
brown to reddish brown, bodies oblanceoloid, 3–3.5 mm, cones conic, 0.8–1 mm, beaks slender, 7.5–10 mm, ribs 4–5 prominent (to 15 fine), faces proximally smooth (faintly tuberculate), muricate in distal 1/4;
pappi yellowish or cream to white, 7–8 mm.
= 24, 40, [16, 32].
Taraxacum officinale
Taraxacum trigonolobum
Taraxacum officinale is the most widespread dandelion in temperate North America, though its abundance decreases in the arid south. It is a familiar weed of lawns and roadsides. It is also the species most commonly used for medicinal and culinary purposes (e.g., E. Small and P. M. Catling 1999).
Phenotypic and genotypic variation of this species have been studied in North America (L. M. King 1993; King and B. A. Schaal 1990; J. C. Lyman and N. C. Ellstrand 1998; O. T. Solbrig 1971; R. J. Taylor 1987), but results of those studies did not lead to the recognition of microspecies.
Specimens of Taraxacum officinale with deeply lobed leaves are sometimes difficult to distinguish from those of T. erythrospermum when fruits are missing (see also R. J. Taylor 1987). Usually, however, early leaves of the former are much less deeply lobed than those of the latter, which are more consistently lacerate throughout development, though broadly winged initially. The two taxa are easily distinguished in fruit, the red cypselae of T. erythrospermum standing out from the dull olive ones of T. officinale.
In northeastern North America, Taraxacum officinale and T. lapponicum often are confused, which has led to reports of the common dandelion farther north than I have been able to verify (it has yet to be collected from the Nunavik region of Quebec, for instance). The characters in the key above help separate the two taxa.
The typification by A. J. Richards (1985) would leave the common dandelion of both Europe and North America without a valid name (J. Kirschner and J. Štepánek 1987). For the time being, with the nomenclatural situation still not resolved, I am following traditional usage of the name Taraxacum officinale.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Taraxacum trigonolobum is known only from the Aleutian Islands and islands of the Bering Sea, on the American side. It is probably the taxonomically weakest entity that I am recognizing in this complex, but its distribution and leaf morphology, among other attributes, are distinctive enough for recognition at the present time.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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