Alocasia baginda Kurniawan & P.C.Boyce

CATE Araceae, 17 Dec 2011. araceae.e-monocot.org

Diagnostic

Alocasia baginda most closely resembles A. melo, notably in the very stiffly thickly coriaceous almost completely peltate leaf blades and pale green glabrous petioles. Vegetatively it is readily distinguished from A. melo by the leaf blades adaxially smooth (not finely and strongly rugose), and dark matte green, with contrasting pale grey bullate portions of the blade. Inflorescences of both species are superficially very similar, although the spathe constriction in A. baginda is situated about mid-way up the staminate flower zone; whereas that of A. melo coincides with the top of the staminate zone, resulting in both the staminate and pistillate zones being enclosed in the lower spathe. Alocasia reginula also closely approaches A. baginda, but is readily differentiated by leaf blades adaxially very dark black-green with white primary and secondary venation, and with wholly deep red abaxial surfaces.

Distribution

Borneo: Eastern Kalimantan, without exact locality.

General Description

Small rather robust terrestrial herb 25–30 cm tall; stem shortly erect, developing in age into a short decumbent rhizome. Leaves up to 4 together, spreading; petioles 13–23 cm long, short sheathing in the lower 1/6–1/7, glabrous, pale green with scattered white speckles in the lower part; sheath persistent; leaf blade very broadly ovate to sub-orbicular, peltate, 10–18 cm long, 7–12 cm wide, stiffly and thickly coriaceous, adaxially matte dark green, with contrasting pale grey bullate portions blade defined by the primary and marginal veins, pale green abaxially, with the distal part of the midrib, primary and marginal veins deep red, apex acuminate to apiculate for ca. 1 cm, thence mucronate for 4 mm; posterior lobes united for 75–90% of their length, 1/2– 1/3 the length of the anterior, with the posterior costae diverging at 20°, anterior midrib with 3–4 primary lateral veins on each side, diverging at 35° (distal ones) to 80–85° (proximal ones); secondary venation impressed adaxially. Inflorescence pairs solitary, each subtended by narrowly membranous prophyll and surrounded by a single membranous cataphyll; peduncle 12–13 cm long, greenish white, exceeding cataphyll; spathe 5–6 cm long; lower spathe abruptly constricted 1.5–2 cm from the base, lower spathe ovoid; spathe limb erect even after anthesis, narrowly elliptictriangular, 3–3.5 cm long, acuminate for ca. 5 mm, externally creamy white, interior glossy creamy white, deep red along the limb margin as far as constriction, limb late in anthesis becoming somewhat semi-translucent with the venation remaining opaque, thence semi-deliquescent; spadix distinctly shorter than to subequalling the spathe, 4–4.5 cm long, stipitate; stipe cylindrical, 2–3 mm long, creamy white; pistillate flower zone 6–7 mm long or about 1/5 the spadix length; pistils rather loosely arranged, ascending; ovaries ovoid, 1.5–2 mm long, ca. 1.5 mm diam., greenish to ivory; style short 0.5–1 mm, < 1 mm diam.; stigma 2–3-lobed, the variation in lobe number present in a single inflorescence, creamy ivory; sterile interstice slender, 2–3mm long, partly naked below and with 6–7 synandrodia above; lowermost synandrodia deeply lobed into almost separate staminodes, the rest rhombohexagonal in plain view, 1–1.5 mm diam.; staminate flower zone cylindric to subcylindrid, 10–11 mm long, ca. 1/4 the length of the spadix, 1/3–1/2 held within the lower spathe chamber, ivory; synandria densely arranged, rhombohexagonal in plan view, convex-topped, 1–1.5 mm diam.; thecae slightly overtopped by the synconnective; appendix 1.75–2 cm long, ca. spadix length, narrowly conic, pale cream. Infructescence and fruits unknown.

Habitat

Unknown. The species to which A. baginda shares closest morphological similarities are locally endemic and obligately associated with limestone (e.g., A. regina N. E. Br.—NE Sarawak: Mulu and A. reginula A. Hay—E Sabah: Bukit Tabin), or ultramafics (A. melo A. Hay, P. C. Boyce & K. M. Wong—E Sabah: Telupid). It is expected that A. baginda will reveal similar geological preference once it is relocated in the wild. It is perhaps worth to note that A. baginda most closely resembles A. melo and A. reginula and that perhaps a search of ultramafic and limestone outcrops is in order.