Platylobium

Taxonomy

Platylobium J.E. Smith Spec. Bot. New Holland 1: 17. 15 Oct 1793.

Subfamily: Faboideae.
Phylogenetic Number: 3.23.07.
Tribe: Bossiaeeae.
Group: Bossiaea.
Species Studied - Species in Genus: 4 studied; 4 in genus.

Description

Fruit: A legume; unilocular; 1.3–5.5 cm long; 0.7–2 cm wide; 0.2 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; not plicate; not twisted; asymmetrical; with 1 straight and 1 curved suture; widest near middle or D-shaped; not inflated; flattened; without beak; rounded at apex, or truncate at apex; oblique with longitudinal axis of fruit; truncate at base; oblique with longitudinal axis of fruit; with the apex and base uniform in texture; chartaceous; seed chambers externally visible; seed chambers with the raised seed chambers not torulose; margin not constricted; margin without sulcus; margin plain, or embellished; margin with wing(s); wing(s) present; wing(s) 2–5; wing(s) 2–3 mm wide; wing(s) sutural; wing(s) on 1 suture (upper); stipitate, or substipitate; with the stipe 0.5–16 mm long; with all layers dehiscing; splitting along suture(s). Dehiscence of valves along both sutures; active; with valves revolute. Replum invisible. Epicarp dull; monochrome; dark reddish brown; with surface texture uniform; glabrous, or pubescent and indurate; with hairs erect; puberulent; with pubescence gray; with pubescence uniformly distributed; 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; solid; chartaceous. Endocarp present; visible; dull; opaque; monochrome; brown and tan (especially dark-brown beneath seeds and tan along wing); smooth; without adhering pieces of testa; nonseptate; chartaceous; not exfoliating; remaining fused to mesocarp and epicarp; with wing(s) extending into epicarp; entire. Seed(s) (1–)2–8; length parallel with fruit length; neither overlapping nor touching; in 1 series. Funiculus 1 mm long; of 1 length only; thick; curved. Aril present; fleshy; when fleshy hooked; entire; covering less than 1/2 of seed; tan.

Seed: 2.5–4 mm long; 1.6–2.5 mm wide; 1.5–1.7 mm thick; not overgrown; not angular; asymmetrical; elliptic, or ovate; compressed; without visible radicle and cotyledon lobes; without hilar sinus; with 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 mottled; with frequent mottles; reddish to dark (nearly black) reddish brown; with black overlay; glabrous; smooth; 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; larger than punctiform; 1.3 mm long; with straight outline; oblong; marginal according to radicle tip; flush; not within corona, halo, or rim. Lens discernible; with margins curved; circular; not in groove of raphe; confluent with hilum (at least hilar rim); flush; dissimilar color from testa; darker than testa; black; 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; less than 1/2 length of cotyledons. Plumule rudimentary; glabrous.

Distribution

Eastern and southern Australia including Tasmania.

Old World; Australia (eastern and southern to Tasmania).

Generic Notes

Ross (1983) monographed the genus.

Tribal Notes

Tribe Bossiaeeae

The Bossiaeeae with ten genera traditionally has been divided into two groups in part on fruit and seed characters. The Templetonia group with the first four genera (including at the time Lamprolobium, 23.02) has non-winged, coriaceous legumes and compressed seeds bearing a collarlike often-lipped aril (except Templetonia biloba (G. Bentham) R.M. Polhill), and a short, straight radicle. The Bossiaea group with the remaining genera has the legumes keeled to winged or not so, plump seeds often covered by a hooded caplike aril (lacking in Muelleranthus (23.08) and Ptychosema (23.09)), and a slender deflexed radicle exserted from the cotyledons. Crisp and Weston (1987, pages 105–107) in their cladistic analysis of the Bossiaeeae, Brongniartieae (22), and Mirbelieae (24), provided compelling evidence that the Bossiaeeae should be redefined to include only the Bossiaea group (genera 23.05–23.10). The Templetonia group would be moved to the Brongniartieae becoming genera three through eight, after Brongniarta (22.01) and Harpalyce (22.02). The proposed generic sequence would be: 3, Templetonia (23.01); 4, Lamprolobium; 5, Plagiocarpus (23.03); 6, ?Genus A (Templetonia incana J.H. Ross); 7, ?Genus B (Templetonia biloba (G. Bentham) R.M. Polhill); and 8, Hovea (23.04). They (Crisp and Weston, 1995) retracted their proposal to transfer the Templetonia group because of Chappill's (1995) cladistic analysis of the entire family, and we have used the traditional circumscriptions of the two tribes (Pohill, 1994a, 1994b).