Alantsilodendron 

Taxonomy

Alantsilodendron J.-F. Villiers Bull. Mus. Natl. Hist. Nat., B, Adansonia 16: 65. 30 Jun 1994.

Subfamily: Mimosoideae.
Phylogenetic Number: 2.3.29A.
Tribe: Mimoseae.
Group: Xylia.
Species Studied - Species in Genus: 1 studied; 9 in genus.

Description

Fruit: A legume; unilocular; 1.8–8.5 cm long; 0.3–0.9 cm wide; 0.4–0.5 cm thick; 2–9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with deciduous calyx; without orifice formed by curving of fruit or fruit segments; straight; not plicate; not twisted; symmetrical; oblong; not inflated; compressed; without beak; tapered at apex; aligned with longitudinal axis of fruit; long tapered 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, or present (Alantsilodendron ramosum Villiers); wing(s) 4; wing(s) 0.5–1 mm wide; wing(s) valvular; nonstipitate; with all layers dehiscing; splitting along suture(s). Dehiscence of valves along both sutures; apical and down; active; with valves reflexing (slightly). Replum invisible. Epicarp dull; monochrome; brown; with surface texture uniform; pubescent and indurate; with hairs appressed; with 1 type of pubescence; puberulent; with pubescence tan; with pubescence uniformly distributed; with simple hairs (antrorse); pliable; with hair bases plain; eglandular; without spines; not smooth; with recessed features; not veined; not tuberculate; grooved (with 1 deep groove running from base to apex, 2–3 mm wide); not exfoliating; without cracks; with embedded tissue, much thicker than epicarp, running from base to apex (the embedded tissue white and very hard, like vegetable ivory). Mesocarp absent. Endocarp present; visible; dull; opaque; monochrome; brown (lighter shade of brown than epicarp); smooth; without adhering pieces of testa; subseptate; with septa thin (tissue paper-like), flexible; with septa eglandular; ligneous; not exfoliating; remaining fused to epicarp; without wings; entire. Seed(s) 4–7; length parallel with fruit length; neither overlapping nor touching; in 1 series. Funiculus 1.5–3 mm long; of 1 length only; filiform; straight, or hooked, or coiled (in wider part of fruit, funiculi straight, and as fruit narrows, funiculi hooked and then coiled in narrowest parts of fruit). Aril absent.

Seed: 3.5–6 mm long; 2–4.5 mm wide; 1.5–1.7 mm thick; not overgrown; not angular; symmetrical, or asymmetrical; ovate, or elliptic, or irregular; 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 wrinkled. Testa present; without pieces of adhering epicarp; not adhering to endocarp; free from endocarp; glossy; not modified by a bloom; colored; monochrome; brown; not smooth; with elevated features; wrinkled; chartaceous. Pleurogram present (darker than the testa, almost black); 95–98 %. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; fully concealed; concealed by funicular remnant; without faboid split (assumed); larger than punctiform; 0.4 mm long; with curved outline; oval; raised; within corona; corona color lighter than testa. Lens discernible; 0.3 mm long; with margins curved; circular; not in groove of raphe; adjacent to hilum; 0.2 mm from hilum; flush; dissimilar color from testa; lighter than testa; white; within halo; halo color darker than testa (black and horse-shaped, surrounding the lens on three sides closest to hilum). Endosperm present (a clear mucoid-like substance); thick; not pluglike and not resembling tip of radicle; covering at least 1/2 of embryo, but not entire embryo; adnate to embryo. Cotyledons smooth; both outer faces flat; both the same thickness; both more or less of equal length; not folded; margin entire 180 degrees from base of radicle; similar at apex; partially concealing radicle; split over radicle; with lobes; with lobes overlapping; with basal groin formed by lobes; with the interface division terminating at base of radicle; without margins recessed; dark brown; inner face flat; glabrous on inner face. Embryonic axis straight; parallel to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; bulbose; lobe tip straight; straight with embryonic axis; centered between cotyledons; less than 1/2 length of cotyledons. Plumule well developed; glabrous.

Distribution

Madagascar.

Old World; Madagascar.

Generic Notes

Villiers (1994) erected the genus Alantsilodendron for eight species from Madagascar, seven of which were formerly in the genus Dichrostachys: A. alluaudianum (R. Viguier) J.-F. Villiers, A. brevipes (R. Viguier) J.-F. Villiers, A. decaryanum (R. Viguier) J.-F. Villiers, A. glomeratum J.-F. Villiers, A. humbertii (R. Viguier) J.-F. Villiers, A. mahafalense (R. Viguier) J.-F. Villiers, A. pilosum J.-F. Villiers, and A. villosum (R. Viguier) J.-F. Villiers. Du Puy et al. (2002) added a ninth species to the genus, A. ramosum Villiers. Fruits and seeds of only A. humbertii were available for study. The valve wall of A. humbertii is unique among legumes. It consists of an epicarp and endocarp, without mesocarp. The epicarp is dark brown, and embedded within it is white, hard tissues which resemble vegetable ivory. The white tissues are completely surrounded by the darker epicarp, and run from the base to the apex of the fruit. Some are small and terete, and others form slabs. The single, large furrow on each valve, running from base to apex, is formed by slab-like tissues embedded in the epicarp. Other species of Alantsilodendron should be studied to determine if these fruit wall structures are unique to all Alantsilodendron species, i.e., a synapomorphy for the genus, or just to A. humbertii. Externally, the fruits of Alantsilodendron and Calliandra (2.5.09) appear to be the same, but the Calliandra thickenings are sutural thickenings and not embedded in the epicarp tissue.