Youngia japonica
in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 7: 194. 1838.
Stems terete, fistulose. Leaves: petioles 1–10 cm, glabrous, puberulent, or densely hairy (hairs often brownish, crinkled); blades 3–12(–25) × 2–4(–6) cm, lateral lobes 0–20, mostly gradually reduced proximally, terminal lobes elliptic, ovate, obovate, or oblong-truncate, larger than laterals, apices obtuse or acute. Peduncles 1–5(–15) mm. Phyllaries 3.5–6 mm, bases and midribs becoming ± spongy, abaxial faces glabrous, glabrate, or hairy (hairs appressed, shining). Florets: corollas mostly 4.5–6.5 mm; anthers dark green (drying purplish); styles and style-branches yellow. Cypselae 1.5–2.5 mm, bases hollow, lightly calloused; pappi 2.5–3.5 mm, slightly surpassing phyllaries. 2n = 16.
Phenology: Flowering spring–summer (year-round south).
Habitat: Waste places, lawns, etc.
Elevation: 0–2400 m
Distribution
Introduced; Ala., Ark., D.C., Fla., Ga., Ky., La., Md., Miss., N.Y., N.C., Pa., S.C., Tenn., Tex., Va., se Asia, introduced also in Mexico, Central America, South America, Europe, Africa, Pacific Islands, Australia.
Discussion
Youngia japonica is now considered a pantropical weed. Relatively few specimens in the flora match what Babcock and Stebbins called subsp. elstonii, with cauline leaves almost as large as the basal and with conspicuous, lobed bracts at the bases of the proximalmost branches of the capitulescence. In subsp. japonica, to which most of our specimens are referred, the cauline leaves are much reduced or lacking, as are the bracts of the capitulescence.
Selected References
None.