A REVIEW OF ALOCASIA (ARACEAE: COLOCASIEAE) FOR THAILAND
compared to the leaf lamina, the pink spathe limb and the representation of elongate stolons arising from a semi-rhizomatous tuber.
4. Alocasia hypoleuca P.C. Boyce sp. nov., ab A. macrorrhizos et alii speciebus Thailandensibus stature majore, foliis subtus glaucis, spatha intus et plus minusve extus glauca, spadice glaucis et synandrodiis minoribus planis et spadice proportione breviore ( minus partem longitudinis spathe) differt. Alocasia macrorrhizos propinquus est sed in habitu caulis erectis non decumbentis et spatha marcescenti distinguitur. Typus: Thailand, SOUTHEASTERN: Chanthaburi, Khao Soi Dao range, road to Ban Tamun, ex. Cult. Forest Herbarium sub. BoyceAL-204 , 23 March 2008 (holotype BKF). Fig. 1.
Very large to massive pachycaul evergreen herb to 3 m with clear latex. Stem erect to ca 2 m or more, slender and self-supporting, very seldom decumbent. Leaves several together, clustered at the tips of stems of larger plants. Petioles to 0.75–1 m long, sheathing in lower
T. Lamina ovato-sagittate, bluntly triangular in general outline, held more or less erect,
ca 100 by 50 cm, light green adaxially, conspicuously glaucous abaxially; primary lateral veins on each side of the anterior costa diverging at ca 60º; glands in axils of primary veins on abaxial side distinct; secondary venation flush with the lamina , forming poorly defined interprimary collective veins; posterior lobes ca –S the length of the anterior, somewhat rotund, naked in the sinus in adult plants, peltate in juveniles. Inflorescences paired among the leaf bases, subtended by membranous cataphylls. Peduncle barely exceeding the cataphylls at anthesis. Spathe ca 24–26cm long, constricted about T of the way from the base; lower spathe ovoid, glaucous yellow-green; limb narrowly oblongo-lanceolate, 20– 22 cm long, cowl-like at anthesis, remaining hooded and then marcescent, pale green, conspicuously glaucous internally, less so externally. Spadix slightly shorter than the spathe, weakly glaucous, sessile; female flower zone ca 3 by 1.5 cm; ovaries globose, ca 2.5 mm diam., mid-green, stigma sessile, 3-lobed, the lobes blunt, deeply incised and erect, deep yellow; sterile interstice ca 2 times the length of the female zone, white, conspicuously narrowed corresponding to the spathe constriction; synandrodia elongated rhombo- hexagonal, ca 5 by 2 mm, the lower ones prismatic and not connate and thus staminodial, distinctly raised, proximally ivory and slightly glaucous, synandrodes on the main, narrowed part of the interstice white; male flower zone cylindric, ca 8 by 1 cm., dirty whitish cream, slightly glaucous; synandria 3–5 androus, rhombo-hexagonal, synconnective flat, ca 1 by 2 mm diam.; appendix less than the length of the spadix, very slightly thicker than the male zone at the base, thence tapering, with conspicuous brain-like patterning of longitudinal grooves, pale cream. Fruiting spathe ovoid, ca 6–9cm long, green. Fruits not observed.
Thailand.— SOUTHEASTERN: Chanthaburi [typus: Khao Soi Dao range, road to Ban Tamun, ex. Cult. Forest Herbarium sub. Boyce AL-204 , 23 March 2008 (holotype BKF)].
Distribution. — Endemic. Ecology. — Dry evergreen forest on granite; altitude ca 500 m. Vernacular. — None recorded. Uses. — None recorded.
Notes. — Alocasia hypoleuca is evidently closely related to A. macrorrhizos but readily distinguished by the very tall, slender, leafless stems that remain self supporting