Podolobium

Taxonomy

Podolobium R. Brown In W. T. Aiton, Hortus Kew. ed. 2. 3: 9. Oct 1811.

Subfamily: Faboideae.
Phylogenetic Number: 3.24.14.
Tribe: Mirbelieae.
Group: Oxylobium.
Species Studied - Species in Genus: 3 studied; 6 in genus.

Description

Fruit: A legumelegume:
usually dry, dehiscent fruit derived from a single carpel that opens along two longitudinal sutures
; unilocular; 0.6–1.5 cm long; 0.2–0.3 cm wide; 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; not plicate; not twisted; symmetrical, or asymmetrical; oblong to ovate; with 1 straight and 1 curved suture, or both sutures parallelly curved; widest near middle or D-shaped, or widest at base; not inflated; terete; with beak; straight; with solid beak the same color and texture as fruit; tapered at apex; aligned with longitudinal axis of fruit, or oblique with longitudinal axis of fruit; tapered at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; chartaceous; seed chambers externally invisible; margin not constricted; margin without sulcus; margin embellished; margin with thickened sutural areas; wing(s) absent; substipitate; with the stipe 1.5–3.5 mm long; with all layers dehiscing; splitting along suture(s). Dehiscence of valves along both sutures; apical and down; weakly active; with valves reflexing (slightly). Replum visible (only at the base of the fruit for 5–15% of length and very rarely up to 50% of fruit length). Epicarp dull; monochrome; brown to tan; with surface texture uniform; pubescent and indurate to glabrous (rarely in Podolobium aciculiferum F.J.H. von Mueller); with hairs appressed, or erect; with 1 type of pubescence; strigose, or villous; with pubescence tan; with pubescence uniformly distributed; with simple hairs; stiff; with hair bases swollen (slightly and persisting on older fruit with the hair shaft missing); eglandular; without spines; not smooth; with elevated features; veined; obliquely veined relative to fruit length and reticulately veined (in the center of the valve), or transversely veined relative to fruit length and reticulately veined (in the center of the valve); 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; glossy; opaque; monochrome; light brown to tan; smooth; without adhering pieces of testa; nonseptate; membranous; not exfoliating; remaining fused to mesocarp and epicarp; without wings; entire. Seed(s) 1–4; length parallel with fruit length; neither overlapping nor touching; in 1 series. Funiculus ca. 1.5 mm long; of 1 length only; filiform; convoluted. Aril present; dry; when dry rim-aril; slightly crenate; covering less than 1/2 of seed; without tongue (or flap) on lips of 2-lipped rim-aril; brown.

Seed: 2–3 mm long; 1.5–1.8 mm wide; 1–1.5 mm thick; not overgrown; not angular; symmetrical; reniform; compressed to terete; with surface smooth; without visible radicle and cotyledon lobes; without hilar sinus, or with shallow hilar sinus (rarely); 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; mottled, or bichrome; with frequent mottles; dark to light brown; with brown overlay; glabrous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; visible, or partially concealed to fully concealed (sometimes); concealed by funicular remnant; with faboid split; with the lips of the faboid split the same color as the rest of the hilum; punctiform to larger than punctiform; 0.2–0.3 mm long; with curved outline; elliptic; apical according to radicle tip but marginal according to seed length; recessed; within halo, or not within corona, halo, or rim; halo lighter than testa. Lens discernible, or not discernible; 0.2–0.3 mm long; with margins curved; elliptic to key-hole shaped; not in groove of raphe; adjacent to hilum; 0.1–0.2 mm from hilum; flush; similar color as testa; lighter than testa, or darker than testa; light to dark brown; not within corona, halo, or rim. Endosperm present; thick; 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; 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; tan; inner face flat; glabrous on inner face. Embryonic axis oblique; oblique to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; bulbose; lobe tip straight; oblique to cotyledons; centered between cotyledons; 1/2 to nearly length of cotyledons. Plumule rudimentary; glabrous.

Distribution

southeastern Australia.

Old World; southeastern Australia.

Generic Notes

Crisp and Weston (1995) and Polhill (1994b) accepted this as a good genus, and we are following Crisp and Weston for distribution and number of species.

Tribal Notes

Tribe Mirbelieae

Crisp and Weston (1987) analyzed the Mirbelieae, and we are following their species counts. We did not treat the following new taxa of Crisp and Weston: the Pultenaea incurvata A. Cunningham group of five species; Pultenaea neurocalyx P.K.N.S. Turczanivow, a one species group; Aotus phyliocides G. Bentham, a one species group; and, Oxylobium microphyllum G. Bentham, a two species genus. The genus Cupulanthus J. Hutchinson is listed on page 85 of Crisp and Weston (1987) and not mentioned by them again. Crisp and Weston (1995) have continued their phylogenetic studies of Mirbelieae, and proposed two major generic changes, the resurrection of Podolobium R. Brown with six species of Oxylobium (24.09, see Notes for Oxylobium) and a new genus, tentatively to be named Otion. Otion, as projected, will have six species, two new ones and four from four different genera: Aotus phylicoides G. Bentham, Burtonia simplicifolia F.J.H. von Mueller & R. Tate, Oxylobium microphyllum G. Bentham, and Phyllota luehmannii F.J.H. von Mueller.