Scientific name: Alocasia vietnamensis V. D. Nguyen & R. J. de Kok
English name:
Vietnamese name: Ráy việt
Other name:

Holotype:

Vietnam, Da Nang province, Ba Na-Nui Chua National Park, 24 Oct 2008, V. D. Nguyen, V. T. Pham, T. C. Vu, H. Q. Bui, R. de Kok, R. P. Clark, C. J. A. M. Sinou, M. D. Xanthos, A. Moore & P. I. Little HNK 3381 (HN!; isotype: K!).

Diagnosis

Alocasia vietnamensis differs from all other species of Alocasia except A. evrardii in having a stipitate spadix with staminodes at the base of the female portion; it differs from A. evrardii in having a rhizomatous stem, peduncles c. ¼ as long as the petioles, and a spathe limb ivory white with a little pale green at the middle outside, white and glossy inside.

Description

Herbs evergreen, slightly robust, 70–80 cm tall; stem rhizomatous, elongate, 2–3 cm in diam., older parts covered by remains of old leaf bases and cataphylls. Leaves up to 5 together; petiole glabrous, red-brown at base, dull green mixed with grey distally, slender, 60–80 cm long, sheathing for 15–25 cm from base, remains persisting as dark brown fibres when dried; blade bright grey abaxially, dark green adaxially, suborbicular to broadly elliptic, 20–33 × 15.5–21.5 cm, base shallowly concave, apex obtuse or rounded; basal lobes adnate for 4–5 cm, subtriangular to semielliptic, 7.5–9 cm long, 7.5–10 cm wide at base; veins: lateral veins 4 or 5 pairs, basal veins c. 3 pairs with smaller veins connecting to a middle vein from lateral veins and toward leaf margin. Inflorescences c. 3 together; peduncle erect at first, then bent down at apex at fruiting, dull green to light brown-grey, 15–23 cm long, covered at base by dark brown cataphylls when decayed; spathe c. 9 cm long; tube pale green outside, light grey inside, elongate subelliptic, c. 30 mm long, c. 8 mm in diam. at middle; limb almost spreading outward at anthesis with apex still convolute, ivory white with a little pale green at middle outside, white and glossy inside, ovate-oblong, c. 6.5 cm long, c. 2.5 cm wide near base, both surfaces smooth, apex acuminate; spadix stipitate, shorter than spathe, c. 7 cm long; stipe white, c. 5 mm long, c. 2.5 mm in diam.; female portion subcylindric, c. 13 mm long, base narrowed, covered by staminodes; sterile portion corresponding with spathe constriction, white, c. 2.5 cm long, c. 5 mm in diam. at base, c. 2.5 mm in diam. at apex, narrower than fertile portions, covered by staminodes; male portion light yellow, subcylindric, c. 13 mm long, c. 3 mm in diam., base oblong, apex truncate; appendix stipitate, dull white, oblong-conical, c. 2.8 cm long, c. 5 mm in diam. at base, apex acuminate; appendix stipe c. 5 mm long, covered by several rows of white ellipsoid synandrodes. Female flowers: ovaries arranged in 2 or 3 rows, unilocular, green, subglobose, c. 2 mm in diam.; stigma dull yellow, broad, slightly concave, with 2 lobes directed upward on both sides; ovules 4 or 5, basal, straight with very short funicle. Male flowers in groups of 2 or 3, c. 1.2 mm long; stipe 0.6–0.7 mm long; thecae conical or cylindrical, c. 0.5 mm long, dehiscing by a pore at apex. Staminodes at base of female portion white, subconical; staminodes of sterile portion long, flattened, parallelogram-shaped.

Distribution

Known only from the type locality in Da Nang province, C Vietnam.

Ecology

Growing as an epiphyte on medium-sized trees in evergreen forests in high wet mountain areas at c. 1560 m above sea level.

Conservation

Although Alocasia vietnamensis is not common in the forest, its propagating capacity is high and it occurs in a National Park. However, details of the distribution, size and stability of its populations are lacking. Therefore, according to IUCN (2012) criteria, we categorize the species as Data Deficient (DD).

Etymology

Alocasia vietnamensis is named after its native country, Vietnam.