Melanthera
squarestem
usually erect or spreading, sometimes sprawling or scandent, branched throughout (± 4-angled and sulcate, usually scabro-hispid, caudices usually ± woody, often ± spheric).
cauline; opposite;
petiolate or nearly sessile;
blades (usually 3-nerved) usually lance-elliptic, linear, oblanceolate, ovate-elliptic, or ovate, sometimes deltate to 3-lobed, bases cuneate to truncate (sometimes hastate or with antrorse basal lobes), margins crenate or serrate (often irregularly), faces usually scabro-hispid, sometimes glabrescent.
± hemispheric or broader, 6–20 mm diam.
flat to convex or convex-hemispheric, paleate (paleae oblanceolate, conduplicate, apices mucronate, pungent, erect or spreading to recurved).
0 [8–15].
20–100+, bisexual;
corollas white [pale to bright yellow], tubes shorter than narrowly funnelform to cylindric throats, lobes 5, ± deltate (anther sacs black; style branches stigmatic in 2 lines, appendages lance-triangular, papillate).
persistent, mostly 8–16 in 2–3 series (mostly ovate to lanceolate, subequal to unequal, bases pallid, with or without green veins, apices herbaceous, tips usually ± mucronate).
discoid [radiate], borne singly or in loose, corymbiform arrays.
(± brown) obpyramidal, (3–)4-angled, not or slightly compressed (striate, rarely verrucose-tuberculate, glabrous);
pappi readily falling, of 2–12 barbellulate bristles or awns.
= 15.
Melanthera
Species ca. 20 (3 in the flora).
Melanthera is common as a strand and weedy plant in Mexico, the West Indies, Central America, South America, and sub-Saharan Africa. In the flora, Melanthera is distinguished by its lack of ray florets, white disc corollas, distinctive cypselae, and delicate, caducous pappus awns. Tilesia G. F. W. Meyer (= Wulffia Necker ex Cassini), Wollastonia de Candolle ex Decaisne, and Echinocephalum Gardner are closely related to Melanthera. The type of Echinocephalum (South America; rays neuter, corollas pale yellow) may be congeneric with that of Melanthera. Inclusion of African species (all radiate) in Melanthera further broadens and complicates its delimitation. H. Wild (1965) broadened the circumscription even more by including the unispecific Wollastonia among African Melanthera species with styliferous ray florets.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Leaf blades usually linear to narrowly lanceolate-oblanceolate, rarely narrowly ovate-elliptic; peduncles glabrescent; phyllaries ovate, 4–5 × 2–3 mm; mucros on paleae 0.5–1 mm, straight to slightly recurved | M. angustifolia |
1. Leaf blades usually ovate, sometimes deltate or 3-lobed, rarely lanceolate-elliptic; peduncles hispid to strigose; phyllaries broadly ovate to lanceolate, 5–7 × 1.5–3 mm, or 3–10 × 3–4 mm; mucros on paleae 0.5–1.5 mm, usually notably recurved | → 2 |
2. Plants 30–60 cm; stems sprawling to weakly erect; leaf blades 1.5–4 × 1–1.5 cm; florets 25–40 | M. parvifolia |
2. Plants 50–220 cm; stems usually erect, sometimes sprawling or scandent; leaf blades 5–12 × 3–8 cm; florets 30–100+ | M. nivea |
WildflowerSearch
iNaturalist
USDA Plants Database
