Sphaerolobium

Taxonomy

Sphaerolobium J.E. Smith Ann. Bot. (König & Sims) 1: 509. 1 Jan 1805.

Subfamily: Faboideae.
Phylogenetic Number: 3.24.02.
Tribe: Mirbelieae.
Group: Daviesia.
Species Studied - Species in Genus: 7 studied; ca. 15 in genus.

Description

Fruit: A legume; unilocular; 0.4–0.55 cm long; 0.3–0.4 cm wide; 0.3–0.4 cm thick; length less than twice as long as width, or 2–9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with deciduous calyx, or persistent calyx; with calyx shorter than fruit; without orifice formed by curving of fruit or fruit segments; straight; not plicate; not twisted; asymmetrical, or symmetrical; more or less circular, or oblong; with 1 straight and 1 curved suture, or both sutures parallelly curved; widest near middle or D-shaped; not inflated; terete; without beak; rounded at apex; aligned with longitudinal axis of fruit; rounded at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; ligneous; seed chambers externally invisible; margin not constricted; margin without sulcus; margin plain; wing(s) absent; substipitate, or stipitate; with the stipe 0.1–5 mm long; with all layers dehiscing; splitting along suture(s). Dehiscence of valves along both sutures; apical and down; passive. Replum invisible. Epicarp dull; monochrome; reddish brown, or tan (to greenish or barely reddish tan), or green, or black; with surface texture uniform; glabrous; eglandular; without spines; not smooth; with elevated features; veined, or not veined; reticulately veined; not tuberculate; wrinkled; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; thick; surface not veined; 1-layered; without balsamic vesicles; without fibers; without reniform canals; solid; (sub-) ligneous. Endocarp present; visible; glossy; opaque; monochrome; reddish brown, or tan, or white (nearly); smooth; without adhering pieces of testa; nonseptate; chartaceous; not exfoliating; remaining fused to mesocarp and epicarp; without wings; entire. Seed(s) 1, or 2; length parallel with fruit length, or transverse to fruit length; neither overlapping nor touching; in 1 series. Funiculus of 1 length only; flattened; straight (from a thickened suture wall). Aril present; dry; when dry rim-aril; entire; tan.

Seed: 1.2–1.8 mm long; 1.1–1.3 mm wide; 0.9 mm thick; not overgrown; not angular; asymmetrical; reniform, or circular, or mitaform; compressed; with surface smooth; without visible radicle and cotyledon lobes, or with visible radicle and cotyledon lobes; without external groove between radicle and cotyledon lobes, or with external groove between radicle and cotyledon lobes; with external groove between radicle and cotyledon lobes same color as testa; 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; reddish brown; glabrous; smooth, or not smooth; with elevated features; tuberculate; coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; partially concealed; concealed by aril; with faboid split; with the lips of the faboid split the same color as the rest of the hilum; punctiform; marginal according to radicle tip; flush; not within corona, halo, or rim, or within rim; rim color of testa. Lens discernible; with margins straight, or curved; oblong; circular, or oblong; not in groove of raphe; adjacent to hilum, or confluent with hilum; 0.2 mm from hilum; 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; split over radicle; with 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

Southwestern and southeastern Australia.

Old World; Australia (southwestern and southeastern).

Generic Notes

The fruits of Sphaerolobium are slightly to noticeably longitudinally compressed so that the long axis is equivalent to the width of most other legumelegume:
usually dry, dehiscent fruit derived from a single carpel that opens along two longitudinal sutures
fruits. The upper fruit in figure A of S. grandiflorum G. Bentham is an example of this compression.

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.