ALOCASIA ACUMINATA
ORIGINAL DESCRIPTION:
“Leaves are elongate-rhombic-saggitate; cuspidate-acuminate, rabbit-like posterior lobes above the petiole insertion, which is closer to the top of the leaf. Sinus is narrow and obtuse. Number of proximal veins equal to distal veins, extending towards the marginal veins approximately in parallel.”
Alocasia acuminata was originally described by Austrian botanist Heinrich Wilhelm Schott in 1859
Bonplandia. Zeitschrift für die gesammte Botanik (Germany) J7 (1859) Page 28
SYNONYMS: 越境海芋 (Pinyin: yuèjìng hǎi yù | “Trans-border Alocasia”)
DISTRIBUTION: Thailand | NORTHERN: Chiang Mai, Phrae; NORTHEASTERN: Khon Kaen; SOUTHWESTERN: Khanchanaburi; NE India | Assam; Nepal; Bangladesh (Type); N Burma; N Laos; N Vietnam (sight record but not confirmed); SW China (sight record not confirmed).
CLIMATE: Ranging from Tropical (hot and humid) in Southern Thailand, to temperate (dry winter, hot summer) in SW China
Humidity is moderately high to high across the region, ranging from 70% to 90%
Temperature across the region can vary, generally staying within the range of 50°F/10°C to 99°F/37°C throughout the year
ECOLOGY: Alocasia acuminata is found in moist areas in dry evergreen forest, sometimes on limestone & granite; altitude: 650–1175 m.
SPECIES DESCRIPTION: Small to medium-sized, slightly robust, evergreen terrestrial herbs to 75 cm tall. Stem rhizomatous, generally elongate, erect later decumbent, ca 8–75 by 2–6 cm diam., older parts covered with remains of old leaf bases and cataphylls. Leaves up to 5 together, subtended by conspicuous lanceolate papery-membranous cataphylls. Petioles glabrous, bright green, ca 15–80 cm long, sheathing in the lower ca 1/4; lamina spreading, narrowly hastato-sagittate to ovato-hastate, 15–60 by 8–20 cm, bright green, posterior lobes 1/4-1/3 the length of the anterior, peltate for 25–30% of their length, acute; anterior costa with 3–6 primary lateral veins on each side, the proximal ones diverging at ca 60–100°, the angle decreasing in distal veins and the course more or less straight to the margin; axillary glands hardly conspicuous abaxially; secondary venation initially wide-spreading, then sooner or later deflected towards the margin; interprimary collecting veins weakly defined.
INFLORESCENCE: Inflorescences usually solitary. Peduncles 9–20 cm long, green, erect at first, then declinate, elongating and then erect in advanced fruit, subtended by a series of progressively larger cataphylls. Spathe 7–10 cm long, moderately constricted ca 1.5–2.5 cm from the base; lower spathe green, ovoid; limb lanceolate, canoe-shaped and longitudinally hooded, 5.5–7.5 cm, membranaceous, very pale green. Spadix subequalling the spathe, ca 6–9.5 cm long, sessile; female flower zone 1–1.5 cm; ovaries subglobose, ca 1.5–2 mm diam., green; stigma subsessile, white, not or only very slightly lobed; sterile interstice 7–10 mm, narrower than the fertile zones, corresponding with the spathe constriction; lower synandrodia often with incompletely connate staminodes, the rest elongate rhombo-hexagonal, flat-topped; male flower zone subcylindric, 1.2–2.5 by 4.5–8 mm, ivory white; synandria 4–6-merous, more or less hexagonal, ca 2 mm diam.; appendix 2.5–3.5 cm long, ca same thickness as male flower zone and demarcated from it by a strong constriction, elongate-conic, white. Fruiting spathe ovoid, ca 3–4 cm long, green. Fruits globose-ellipsoid, ca 0.75 cm diam, green, ripening orange-red.
VARIEGATED FORMS: N/A
NOTES: Alocasia acuminata is most similar to Alocasia longiloba but readily separable by the unlobed or barely lobed stigma, bright green leaf laminae, plain green petioles and cataphylls and in always having several leaves together. The sessile spadix and unlobed stigmas are diagnostic in Thailand.
