Subfamily: Faboideae.
Phylogenetic Number: 3.7.
Tribe: Millettieae.
Species Studied - Species in Genus: 2 studied; 3 in genus.
Fruit: A legume; unilocular; 7–10 cm long; 2–2.5 cm wide; 0.75–0.9 cm thick; 2–9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with persistent calyx; with calyx shorter than fruit; without orifice formed by curving of fruit or fruit segments; straight, or curved (slightly); not plicate; not twisted; asymmetrical, or symmetrical; oblong, or lanceolate; with both sutures parallelly curved; not inflated; flattened; without beak; long tapered at apex; oblique with longitudinal axis of fruit; short tapered at base, or rounded at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; membranous; seed chambers externally visible; margin not constricted, or constricted; margin slightly constricted only on 1 margin; margin without sulcus; margin embellished; margin with wing(s) and fringe (reddish-brown hairs along sutures of D. nyasae); wing(s) present (both species have wing fruit though wing is inconspicuous); wing(s) 1; wing(s) 0.1–30 mm wide; wing(s) samaroid, or continuous wing around fruit; wing(s) on both sutures; substipitate; indehiscent. Replum invisible. Epicarp dull; monochrome; brown (greenish), or tan (with reddish-brown fringe); with surface texture uniform; pubescent and indurate, or glabrous; with hairs erect; with 1 type of pubescence; puberulent; with pubescence golden; with pubescence uniformly distributed; with simple hairs, or complex hairs (plumose hairs especially along sutures in D. nyasae); pliable; with hair bases plain; eglandular; without spines; not smooth; with elevated features; veined; reticulately veined; not tuberculate; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; thin; surface not veined; 1-layered; without balsamic vesicles; without fibers; without reniform canals; spongy; chartaceous. Endocarp present; visible; glossy; opaque; monochrome; brown (golden); smooth; without adhering pieces of testa; nonseptate; chartaceous; not exfoliating; remaining fused to mesocarp and epicarp; with wing(s) extending into epicarp (both species have wing fruit though wing is inconspicuous); entire. Seed(s) 1; length parallel with fruit length. Funiculus 0.5–70 mm long; filiform; straight. Aril present (D. nyasae), or absent (D. welwitschii (E.G. Baker) E.G. Baker); fleshy; when fleshy knotty; entire; covering less than 1/2 of seed; tan.
Seed: 12–15 mm long; 6–10 mm wide; 1.8–2 mm thick; not overgrown; not angular; asymmetrical; D-shaped, or reniform; flattened; with surface smooth; without visible radicle and cotyledon lobes; without hilar sinus; without umbo on seed faces; without medial ridge on each face. Cuticle not exfoliating; not inflated; not wrinkled. Testa present; without pieces of adhering epicarp; not adhering to endocarp; free from endocarp; dull; not modified by a bloom; colored; monochrome, or streaked; with frequent streaks; brown (reddish); with brown overlay (bright reddish); glabrous; smooth; coriaceous, or chartaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; visible; with faboid split; with the lips of the faboid split the same color as the rest of the hilum; larger than punctiform; 1 mm long; with straight outline; oblong; marginal according to radicle tip, or between cotyledon and radicle lobe; flush; not within corona, halo, or rim. Lens not discernible. Endosperm present; thin; not pluglike and not resembling tip of radicle; covering entire embryo; adnate to testa. Cotyledons smooth; both outer faces convex; both the same thickness; both more or less of equal length; not folded; margin entire 180 degrees from base of radicle; similar at apex; partially concealing radicle; notched at radicle; without lobes; with the interface division terminating at base of radicle; without margins recessed; tan; inner face flat; glabrous on inner face. Embryonic axis deflexed; oblique to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; linear; lobe tip straight; deflexed and parallel to cotyledon width; centered between cotyledons; less than 1/2 length of cotyledons. Plumule rudimentary; glabrous.
Geesink (1981) placed Dalbergiella in the Tephrosieae (now Millettieae), but in Geesink (1984) the genus is transferred to the Dalbergieae without relating Dalbergiella to other genera in the Dalbergieae. The fruits of Dalbergiella nyasae and D. welwitschii are similar in many respects, but there is one significant difference. The fruits of D. nyasae are tan with a reddish-brown fringe composed of plumose hairs along the sutures, while D. welwitschii is greenish-brown and the sutures are entire and the hairs are simple. The seeds of D. nyasae also have an aril, which is absent on seeds of D. welwitschii. It is unfortunate that we were unable to study fruits and seeds of the third species: D. gossweileri E.G. Baker.
Tribe Millettieae
Geesink (1981) treated this tribe, as others before him, under the tribal name Tephroseae, but we now know that its correct name is Millettieae. Recent tribal studies (Geesink, 1981, 1984; Polhill, 1994a, 1994b) have arranged the genera in alphabetical order without phylogenetic numbers. Geesink (1984) monographed tribe Millettieae, and presented descriptive notes about fruits and seeds and in situ fruit and seed drawings. However, we are not entirely following Geesink (1984) for generic parameters because he either questioned the status of many of his new genera or did not make the necessary species transfers. The few new genera which he clearly recognized are being accepted. Lavin et al. (1998) developed a preliminary infratribal classification of six informal groups using phytochrome nucleotides: Millettia group, Lonchocarpus group, Derris group, Tephrosia group, "primitive" group, and Phaseoleae group. Lavin (1987) transferred Sphinctospermum to Millettieae. Lavin and Doyle (1991) carried out cladistic analyses integrating morphological and chloroplast DNA data, and concluded that it is a member of Robineae where we have placed it (now 8.12).
Authors: J.H. Kirkbride, Jr., C.R. Gunn, A.L. Weitzman, M.J. Dallwitz, K.R. Thiele
Content last updated April 2003
Released April 2024 on idtools.org
