Burkea

Taxonomy

Burkea W.J. Hooker Icon. Pl. t. 593, 594. Jul 1843.

Subfamily: Caesalpinioideae.
Phylogenetic Number: 1.1.45.
Tribe: Caesalpinieae.
Group: Dimorphandra.
Species Studied - Species in Genus: 1 studied; 1 in genus.

Description

Fruit: A legume; unilocular; 4–7.5 cm long; 1.8–3 cm wide; 0.2–0.4 cm thick; 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; not plicate; not twisted; asymmetrical; elliptic to oblong; not inflated; flattened; without beak; tapered at apex; aligned with longitudinal axis of fruit; long tapered at base; curved to 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 visible; margin not constricted; margin without sulcus; margin plain; wing(s) absent; stipitate; with the stipe 6–15 mm long; indehiscent. Replum invisible. Epicarp dull; monochrome; reddish brown; with surface texture uniform; minutely pubescent and indurate; with hairs erect; eglandular; without spines; not smooth; with elevated features; veined; reticulately veined and longitudinally veined relative to fruit length (strongly); not tuberculate; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; surface not veined; 2-layered; without balsamic vesicles; without fibers; without reniform canals; with solid layer over spongy layer; coriaceous. Endocarp present; visible; glossy; opaque; monochrome; brown; without adhering pieces of testa; septate; not exfoliating; remaining fused to mesocarp and epicarp; entire. Seed(s) 1; length parallel with fruit length. Funiculus 0.1–5 mm long; of 1 length only; thick; curved. Aril absent.

Seed: 7–12 mm long; 6–8 mm wide; 3–4 mm thick; not overgrown; not angular; symmetrical; 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; dull; not modified by a bloom; colored; monochrome; brown; glabrous; smooth; osseous. Pleurogram present; 90 %. Pseudopleurogram absent. Fracture lines present; reticulate. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; fully concealed; concealed by funicular remnant; without faboid split; punctiform; apical at apex of radicle tip; flush; not within corona, halo, or rim. Lens discernible; 0.6 mm long; with margins curved; elliptic; not in groove of raphe; recessed; dissimilar color from testa; black; not within corona, halo, or rim. Endosperm present; thick; not pluglike and not resembling tip of radicle; 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; with lobes; with lobes not touching; 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; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; centered between cotyledons. Plumule rudimentary; glabrous.

Distribution

Generic Notes

Externally, Seeds of B. africana resemble pleurogrammatic seeds of the Mimosoideae. Internally, the cordate cotyledon with lobes investing the exposed radicle is a frequently observed character of the Caesalpinioideae, but an infrequently observed character of the Mimosoideae.