Mikania

Willdenow

Sp. Pl. 3: 1742. 1803

Common names: Climbing hempweed
Etymology: For Josef Gottfried Mikan, 1743–1814, professor, University of Prague
Treatment appears in FNA Volume 21. Treatment on page 545. Mentioned on page 459, 546.
Vines (perennial, sometimes suffrutescent) [non-viney perennials, shrubs], to 300[–1500+] cm. Stems usually twining to scrambling (terete, striate, or [4-] 6-angled, sometimes winged), branched. Leaves cauline; opposite [whorled]; petiolate [sessile]; blades palmately 3[–7]-nerved [pinnately nerved], ± ovate or deltate-ovate to triangular [linear], margins entire or undulate to dentate or toothed to lobed, faces glabrous or puberulent to tomentose, often gland-dotted. Heads discoid, in corymbiform [paniculiform, racemiform, spiciform, thyrsiform] arrays. Involucres ± cylindric, [1–]2–3[–4] mm diam. (usually each subtended by 1 bractlet). Phyllaries persistent, 4 in ± 2 series (outer pair imbricate over inner pair), not notably nerved, lanceolate, linear, or oblong (bases often swollen), ± equal. Receptacles flat (glabrous), epaleate. Florets 4; corollas usually white, sometimes pink to rose or purplish, throats funnelform or campanulate, lobes 5, linear or triangular to deltate; styles: bases slightly, if at all, enlarged, glabrous, branches ± filiform [weakly clavate]. Cypselae ± prismatic, [4–]5[–10]-ribbed, glabrous or puberulent, sometimes gland-dotted; pappi persistent, of [20–]30–60 (white, buff, pinkish, or purplish) barbellulate to barbellate bristles in 1–2 series (distinct or basally connate). x = 16–20.

Distribution

Overwhelmingly neotropical (9 species in the Old World tropics), some temperate North American and South American.

Discussion

Species ca. 450 (3 in the flora).

All species of Mikania in the flora belong to M. sect. Mikania in the sense of W. C. Holmes (1996).

Lower Taxa

Key

1 Stems 6-angled, gray-tomentulose to tomentose; leaf blades ovate to deltate; heads 7–10 mm; phyllaries 6–8 mm; corolla lobes linear; cypselae 3–4 mm Mikania cordifolia
1 Stems terete to obscurely 6-angled, glabrate to densely pilose; leaf blades triangular to triangular-ovate; heads 4–7 mm; phyllaries 3–6 mm; corolla lobes triangular to deltate; cypselae 1.8–2.2 mm > 2
2 Leaves (membranous): apices tapering; phyllaries linear-lanceolate, 5–6 mm; corollasusually pinkish to purplish, 3.5–4 mm; e United States Mikania scandens
2 Leaves (subcoriaceous to ± fleshy): apices acute to acuminate; phyllaries lanceolate tonarrowly ovate, 3–4 mm; corollas white, ca. 3 mm; s Florida Mikania batatifolia