Humboldtia

Taxonomy

Humboldtia M.H. Vahl Nom. cons. Symb. Bot. 3: 106. 1794.

Subfamily: Caesalpinioideae.
Phylogenetic Number: 1.4.73.
Tribe: Detarieae.
Group: Amherstia.
Species Studied - Species in Genus: 2 studied; 5 in genus (F.R. Rickson, pers. comm. 1999).

Description

Fruit: A legume; unilocular; 5–12 cm long; 2–4.5 cm wide; ?; 2–9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with deciduous calyx; without orifice formed by curving of fruit or fruit segments; straight to curved; not plicate; not twisted; symmetrical, or asymmetrical; oblong, or falcate; with both sutures parallelly curved, or 1 straight and 1 curved suture; widest near middle or D-shaped, or widest near apex; not inflated; compressed; without beak; long tapered at apex; aligned with longitudinal axis of fruit to oblique with longitudinal axis of fruit; tapered at base; aligned with longitudinal axis of fruit to oblique with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous; seed chambers externally invisible; margin not constricted; margin without sulcus; margin plain; wing(s) absent; substipitate; with all layers dehiscing; splitting along suture(s). Dehiscence of valves along both sutures; active; with valves separately enrolling. Replum invisible. Epicarp dull; monochrome; brown to reddish brown; with surface texture uniform; glabrous to pubescent and indurate (velvety); with hairs erect; with simple hairs; eglandular; without spines; not smooth; with elevated features; veined; obliquely veined relative to fruit length; not tuberculate; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; surface not veined; 1-layered; without balsamic vesicles; without fibers; without reniform canals; solid; coriaceous. Endocarp present; visible; dull; opaque; monochrome; tan; without adhering pieces of testa; nonseptate; not exfoliating; remaining fused to mesocarp and epicarp; entire. Seed(s) 2–6; length transverse to fruit length; neither overlapping nor touching; in 1 series. Funiculus 1.1–2 mm long; of 1 length only; thick; straight. Aril absent.

Seed: 14–20 mm long; 10–15 mm wide; 3–4 mm thick; not overgrown; not angular; symmetrical; ovate to oblong; compressed; 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; nearly glossy; not modified by a bloom; colored; monochrome; reddish brown; glabrous; not smooth; with elevated features; rugose; chartaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; fully concealed; concealed by funicular remnant; without faboid split; larger than punctiform; 0.1–1.5 mm long; shape not specified; apical at apex of radicle tip; flush; not within corona, halo, or rim. Lens not discernible. Endosperm absent. 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 (only tip exposed); notched at radicle and split over radicle; with the interface division terminating at base of radicle; without margins recessed; inner face flat; glabrous on inner face. Embryonic axis straight; parallel to length of seed to oblique to length of seed (slightly); without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; centered between cotyledons. Plumule rudimentary; glabrous.

Distribution

Southern India and Ceylon.

Old World; Southern India (and Ceylon).

Generic Notes

Sanjappa (1986) revised the genus recognizing six species and two varieties.

Tribal Notes

Tribe Detarieae

Bruneau et al. (2000) carried out extensive phylogenetic analyses of tribes Amherstieae and Detarieae. They concluded that they form a single monophyletic group. Therefore, they supported Polhill's (1995a, 1995b) decision to unite the two tribes.