Ptychosema

Taxonomy

Ptychosema G. Bentham ex J. Lindley Sketch Veg. Swan River Colony xvi. 1 Nov 1839.

Subfamily: Faboideae.
Phylogenetic Number: 3.23.09.
Tribe: Bossiaeeae.
Group: Bossiaea.
Species Studied - Species in Genus: 1 studied; 2 in genus.

Description

Fruit: A legumelegume:
usually dry, dehiscent fruit derived from a single carpel that opens along two longitudinal sutures
; unilocular; 1.4–2.2 cm long; 0.45–0.5 cm wide; 0.08 cm thick; 2–9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with persistent calyx; with calyx shorter than fruit; straight; not plicate; not twisted; symmetrical; oblong; not inflated; flattened; without beak; short tapered at apex, or emarginate at apex; aligned with longitudinal axis of fruit; rounded at base; aligned with longitudinal axis of fruit, or oblique with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous; seed chambers externally visible (faintly), or invisible; seed chambers with the raised seed chambers not torulose; margin not constricted; margin without sulcus; margin plain; wing(s) absent; stipitate, or substipitate; with the stipe 4–7 mm long. Replum invisible. Epicarp dull; multicolored; mottled and streaked; tan; with brown overlay (reddish); mottling color combination constant; with surface texture uniform; glabrous; 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; coriaceous. Endocarp present; visible; dull; opaque; monochrome; tan; smooth; without adhering pieces of testa; nonseptate; chartaceous; not exfoliating; remaining fused to mesocarp and epicarp; without wings; entire. Seed(s) 2–7; length parallel with fruit length; neither overlapping nor touching; in 1 series. Funiculus of 1 length only; thick; straight. Aril present; dry; when dry tongue-aril; entire; white.

Seed: 2.3–2.5 mm long; 1.7–2 mm wide; 0.5–0.7 mm thick; not overgrown; not angular; symmetrical (except for hilum); elliptic 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; dull; not modified by a bloom; colored; monochrome; black (blackish-brown when mature), or green (greenish-brown when immature); 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; without faboid split; punctiform; marginal according to radicle tip; flush; within halo; halo lighter than testa. Lens faintly discernible; with margins curved; circular; not in groove of raphe; adjacent to hilum; 0.1–0.2 mm from hilum; barely mounded; similar color as testa (but in lighter colored halo); within halo; halo color lighter than testa. 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 not 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

Central and western Australia.

Old World; Australia (western and central).

Generic Notes

The fruits and seeds of the type species, Ptychosema pusillum G. Bentham, are not known to science (Lee, 1973).

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).