Polhillia

Taxonomy

Polhillia C.H. Stirton S. African J. Bot. 52: 170. 16 Apr 1986.

Subfamily: Faboideae.
Phylogenetic Number: 3.30.04.
Tribe: Genisteae.
Species Studied - Species in Genus: 3 studied; 7 in genus.

Description

Fruit: A legumelegume:
usually dry, dehiscent fruit derived from a single carpel that opens along two longitudinal sutures
; unilocular; 1.5–4 cm long; 0.3–0.6 cm wide; 0.2–0.3 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, or plicate; not twisted; asymmetrical, or symmetrical; nearly oblong, or linear; with both sutures nearly straight; not inflated; flattened; without beak; short tapered at apex; aligned with longitudinal axis of fruit; short tapered at base; with the apex and base uniform in texture; chartaceous, or ligneous (according to Stirton (1986b)); seed chambers externally visible; seed chambers with the raised seed chambers torulose; margin not constricted; margin without sulcus; margin plain; wing(s) absent; substipitate; indehiscent. Replum invisible. Epicarp dull; monochrome; dark brown to black (but appearing gray because of hairs); with surface texture uniform; pubescent and indurate; with hairs erect; with 1 type of pubescence; villous; with pubescence gray; with simple hairs; pliable; with hair bases plain; eglandular; without spines; not smooth; with elevated features; not veined; not tuberculate; shagreen (is this best?); 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; grayish brown; smooth; without adhering pieces of testa; nonseptate (but fruit impressed between seeds); chartaceous; not exfoliating; remaining fused to mesocarp and epicarp; without wings; entire. Seed(s) 4–8; length parallel with fruit length; neither overlapping nor touching; in 1 series. Funiculus of 1 length only; triangular, or thick; straight, or curved (slightly). Aril present; dry; when dry rim-aril; entire; reddish brown.

Seed: 2.3–3 mm long; 2.3–3 mm wide; 2–2.2 mm thick; not overgrown; not angular; asymmetrical; obliquely cordate, or mitaform; compressed; with visible radicle and cotyledon lobes; without external groove between radicle and cotyledon lobes; with umbo on seed faces (nearly); with umbo on both faces of seed; 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 (if green may be blotchy purple but not mottled and streaked); greenish to dark brown, or tan; glabrous; smooth, or not smooth; with elevated features; wrinkled (based on seed and not testa characters); coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; fully concealed; concealed by aril; 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; recessed; within rim; rim color darker than testa. Lens discernible; 0.7 mm long; with margins straight; wedge-shaped; not in groove of raphe; adjacent to hilum; mounded; dissimilar color from testa; lighter than testa, or darker than testa; black, or tan; not within corona, halo, or rim. 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; 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; linear; deflexed and parallel to cotyledon length; centered between cotyledons; 1/2 to nearly length of cotyledons. Plumule moderately developed; glabrous.

Distribution

South Africa (Southwestern Cape Province).

Old World; Africa (South).

Generic Notes

Stirton (1986b) when he founded the genus, noted that Polhillia "has a natural affinity with Melobium and Dichilus", (30.01) and (30.02) respectively. Polhill (1981q) and Van Wyk (1991) had this genus in Crotalarieae, but later transferred it to the beginning of the Genisteae (30; Polhill, 1994a, 1994b; Van Wyk and Schutte 1995a). Its number of species and distribution taken from Van Wyk (1991)and Van Wyk and Schutte (1995a).

Tribal Notes

Tribe Genisteae

Traditionally this tribe has been called Genisteae. Reveal (1997) reported that the name Cytiseae was published before the name Genisteae. Following the International Code of Botanical Nomenclature (Greuter et al., 1994), the oldest name for a taxon must be used, so Reveal suggested that this tribe should be called Cytiseae. In 1999 Reveal (1999) reversed himself, so that this tribe remains the Genisteae. Bisby (1981) summarized tribe Genisteae, following the excellent study by Polhill (1976). Bisby correctly noted that "many species have been moved from one genus to another several times and the Cytisus-Genista complex has gained a reputation as a critical group." He continued with an indepth analysis of the tribe. Polhill (1994a, 1994b) and Van Wyk and Schutte (1995a), using chemical and morphological characters, transferred five genera from Crotalarieae (27) to Genisteae: Anarthrophyllum (30.06), Argyrolobium (30.03), Dichilus (30.02), Melolobium, and Sellocharis (30.07). Cristofolini (1997) carried out a cladistic study of the tribe's biogeography, and discussed its early evolutionary history. López et al. (2000) studied the species of this tribe occurring in southwestern Spain and presented detailed descriptions for and a key to them.