Pearsonia

Taxonomy

Pearsonia R.A. Dümmer J. Bot. 50: 353. Dec 1912.

Subfamily: Faboideae.
Phylogenetic Number: 3.27.01.
Tribe: Crotalarieae.
Species Studied - Species in Genus: 7 studied; 12 in genus.

Description

Fruit: A legume; unilocular; 0.5–3.8 cm long; 0.25–0.8 cm wide; 0.7–0.8 cm thick; 2–9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with persistent calyx; with calyx equal in length to fruit, or shorter than fruit; without orifice formed by curving of fruit or fruit segments; straight, or curved (slightly); not plicate; not twisted; asymmetrical, or symmetrical; elliptic, or oblong (lanceolate); with both sutures nearly straight; not inflated; compressed; without beak, or with beak (Pearsonia madagascariensis (R. Vig.) Polhill, Du Puy et al., 2002); straight; with solid beak the same color and texture as fruit; tapered at apex; aligned with longitudinal axis of fruit; tapered at base; aligned 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; nonstipitate; with all layers dehiscing; splitting along suture(s). Dehiscence of valves along both sutures; apical and down; assumed active; with valves twisting (assumed). Replum invisible. Epicarp dull; monochrome; brown (because of numerous golden hair); with surface texture uniform; pubescent and indurate; with hairs erect; with 1 type of pubescence; pilose, or tomentose, or villous, or sericeous; with pubescence golden; with simple hairs; pliable; with hair bases plain; eglandular; without spines; not smooth; with elevated features; veined, or not veined; reticulately veined; not tuberculate; shagreen (may not be best answer); 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; solid; coriaceous. Endocarp present; visible; dull; opaque; monochrome; brown; smooth; without adhering pieces of testa; nonseptate; chartaceous; not exfoliating; remaining fused to mesocarp and epicarp; without wings; entire. Seed(s) 1–15; length parallel with fruit length; neither overlapping nor touching; in 1 series. Funiculus of 1 length only; thick; straight. Aril absent.

Seed: 2–2.5 mm long; 1.7–2 mm wide; 1.4–1.5 mm thick; not overgrown; not angular; asymmetrical; obliquely cordate, or reniform; compressed; with visible radicle and cotyledon lobes, or without visible radicle and cotyledon lobes; without external groove between radicle and cotyledon lobes; 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; glossy; not modified by a bloom; colored; monochrome; brown, or tan; glabrous; smooth; coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; visible, or fully concealed; concealed by funicular remnant; with faboid split; with the lips of the faboid split the same color as the rest of the hilum; punctiform; between cotyledon and radicle lobe; flush; within rim; rim color of testa, or lighter than testa. Lens discernible; 0.5–0.7 mm long; with margins straight, or curved; linear, or oblong; oblong; not in groove of raphe; adjacent to hilum; 0.1 mm from hilum; mounded; dissimilar color from testa; darker than testa; reddish brown; not within corona, halo, or rim. Endosperm present; thin; not pluglike and not resembling tip of radicle; covering entire embryo; adnate to embryo. Cotyledons smooth; both outer faces convex; both the same thickness; both more or less of equal length; not folded; similar at apex; not concealing radicle; entire over radicle; without lobes; with the interface division terminating at base of radicle; without margins recessed; yellow; 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; bulbose; deflexed and parallel to cotyledon length; centered between cotyledons; less than 1/2 length of cotyledons. Plumule rudimentary; glabrous.

Distribution

Africa (South of the equator) and Madagascar (1 sp.).

Old World; south of equator in Africa to Madagascar.

Generic Notes

Polhill (1974) monographed Pearsonia.

Tribal Notes

Tribe Crotalarieae

Polhill (1981q) broadly defined tribe Crotalarieae with two generic groups. The first group, without a two-lipped calyx, formed a tight cluster around Lebeckia (3.27.10) in southern Africa. The second group, with a two-lipped calyx, had more scattered distributions and uncertain affinities. Van Wyk (1991) followed Polhill (1981q), and transferred Argyrolobium (3.30.03) from Genisteae (3.30) to the second group. Crotalarieae and related tribes are rich in alkaloids which have been extensively studied in the last decade (Hussain et al. 1988; Van Wyk and Verdoorn, 1989a, 1989b, 1989c, 1990, 1991a, 1991b; Van Wyk et al., 1989, 1993; Verdoorn and Van Wyk, 1990, 1991). Polhill (1994a, 1994b) and Van Wyk and Schutte (1995a), using chemical and morphological data, restricted Crotalarieae to the genera without a two-lipped calyx, and transferred those with a two-lipped calyx to Genisteae, Anarthrophyllum (3.30.06), Argyrolobium (3.30.03), Dichilus (3.30.02), Melolobium (3.30.01), and Sellocharis (3.30.07), except Lebeckia. They also more or less inverted the generic order within the first group according to Van Wyk and Schutte's cladistic analysis for the genera of Crotalarieae, in the narrow sense.