Desmanthus virgatus
Desmanthus leptophyllus
wild tantan
slenderleaf bundleflower
glabrous or sparsely pubescent with short white hairs along ribs, glabrescent.
glabrous.
1–3[–6.5] cm;
stipules persistent, 2.1–9 mm, with membranous, prominently veined auricle opposite petiole, glabrous or pubescent;
petiole 1–5 mm;
pinnae 2–5 pairs;
nectary present, sessile, crateriform, interpinnal between proximal pair of pinnae;
leaflets 22–46, blades 2.7–7 mm, venation obscure except for eccentric midvein, surfaces glabrous.
4.4–11 cm;
stipules persistent, 3.3–9.5 mm, with small, membranous margins at base, glabrous or pubescent;
petiole 3–14 mm;
pinnae 4–8 pairs;
nectary sessile, crateriform or flattened, between proximal pair of pinnae, rarely also between distal pairs of pinnae;
leaflets 32–72, blades 2.1–5.7 mm, venation obscure except for nearly centric midvein, surfaces glabrous.
0.6–4 cm, 1–5.2 cm in fruit.
0.8–2.7 cm, 1–3.3 cm in fruit.
stamens 10;
staminodia 1.5–7.5 mm;
style not exserted beyond stamens.
stamens 10;
staminodia 0.5 mm;
style not exserted beyond stamens.
reddish brown to nearly black, straight or weakly falcate, linear, not constricted between seeds, dehiscent along both sutures, 2.2–6[–8.8] cm × 2.5–4 mm, apex acute to attenuate.
reddish brown to nearly black, usually straight, sometimes recurved, linear, not constricted between seeds, dehiscent along both sutures, 5.5–8.5 cm × 3.2–5 mm, apex acute, apiculate with beak to 3 mm.
1 per axil, 3–22-flowered, sometimes only bisexual flowers present;
sterile flowers 0–8 per head; staminate and bisexual flowers 3–14 per head.
1 per axil, 5–12-flowered;
sterile flowers 0(1 or 2) per head; staminate and bisexual flowers 5–11 per head.
= 28.
Desmanthus virgatus
Desmanthus leptophyllus
Desmanthus virgatus was the umbrella species in the genus for any taxon with inconspicuous flowers and unspecialized legumes; D. acuminatus, D. brevipes, and D. glandulosus have at times been considered varieties of this species, and D. leptophyllus and D. pernambucanus were synonymized with it in the tropics. The confusion is understandable because species differ in characteristics that may be difficult to see on a herbarium specimen, such as habit, degree of branching, taproot color and shape, and sleep movements of the leaves. Common garden studies (M. A. Luckow 1993) demonstrated that such characteristics are not phenotypic plasticity but have a genetic basis. In the flora area, D. virgatus is less variable than in Mexico, where one sees more erect forms with larger fruits and more flowers per inflorescence.
Desmanthus virgatus, as here circumscribed, is found throughout warmer areas in the New World; Old World species that have previously been considered D. virgatus are best referred to D. pernambucanus. Desmanthus virgatus has been intensively studied as a potential source of livestock feed for tropical areas.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Part of the Desmanthus virgatus complex, D. leptophyllus differs from D. virgatus in the flora area by having more pinnae and leaflets and an erect rather than decumbent or prostrate habit. In the flora area, it is known from relatively few collections and is likely introduced.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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