Tên Khoa học: Homalomena vietnamensis J. Bogner & V. D. NguyenTên tiếng Anh: Tên tiếng Việt: Môn việt; Môn lá xoanTên khác:
Holotypus: Cultivated from the sterile wild source “Vietnam, Thua Thien-Hue province, Bach Ma National Park, 1997, Bogner 2810”, flowering herbarium specimen prepared on 22.7.2008, Bogner 2810a (M).
Plant herbaceous, adult specimens 50-60 high. Stem erect, 20-30 cm high and 1.8-2 cm in diam., only old long stems decumbent, old stems covered with dry, brown leaf remnants; internodes short (c. 0.5 cm long); roots 2-3 mm in diam., branched (second order roots much thinner); upper stem portion with several subhorizontally spread leaves. Petioles 25-35 cm long, near base 0.7 cm and near apex 0.5 cm in diam., mid green, most of its length terete, distally on upper side slightly flattened at a length of 3-5 cm, non-geniculate. Leaf sheath 13-18 cm long and well developed, persistent (as long as the leaf is alive) and in the middle 1-2 cm broad, apex of sheath acute. Leaf blade broadly ovate, 17-20 cm long and 13-18 cm wide (nearly as broad as long) [only juvenile leaves somewhat narrower and with an obtuse base], base (of adult leaves) always truncate to obtuse (never cordate!), apex cuspidate with a (3-)4-5 mm long mucro, blade above dark green and glossy, underneath more or less light green and not glossy; venation parallel-pinnate, 6-7(-8) primary lateral veins on each side of the strong mid vein and with a distance of 1-2 cm from each other, sunken above and prominent underneath, second order veins thinner and parallel between the primary ones, third order veins much thinner and very close to each other. Cataphylls 8-15 cm long, light green with reddish tinge. Inflorescences shorter than petioles, 1-3 in a sympodium. Peduncle 12-14 cm long and 0.4-0.5 cm in diam., terete and somewhat thicker below spathe, ± greenish and reddish tinged, peduncle first erect, after anthesis bent (and turned downwards). Spathe (6.5-)7-8 cm long and c. 2 cm in diam. in the middle, non-constricted, thick, ending in a 3-4 mm long mucro, dark green outside and very light green to whitish inside, convolute and closed after anthesis. Spadix 3-3.5 cm long, cylindric (only nearly half the length of the spathe), with a stipe c. 2 mm long and 4 mm in diam., greenish white; female zone 1.3-1.5 cm long and 0.7 cm in diam.; male zone 1.5-1.8 cm long and c. 0.7 cm in diam., slightly ellipsoid, cream-coloured, apex blunt, fertile to the apex. Flowers unisexual, naked. Female flowers densely arranged; gynoecium ovoid, c. 2 mm tall, with one much shorter staminode each; ovary 1.1-1.2 mm in diam., greenish white, usually with 3 parietal placentae, ovules hemianatropous, many; style attenuate, 0.5-0.6 mm long, of the same colour as the ovary; stigma discoid, 0.6-0.7 mm in diam., ± as broad as style, whitish brown; staminode slender, subcylindric to slightly clavate, 1- 1.1(-1.2) mm long, whitish. Male flowers consisting of usually (2-)3-4 free stamens, often somewhat irregularly arranged; stamen truncate, c. 1 mm tall, subrectangular in view from above, c. 1 mm long and 0.7-0.8 mm wide; between female and male flowers two rows of single stamens or staminodes (some very similar to stamens but lacking thecae); pollen grains inaperturate, ellipsoid, 20-22 µm long and 15-17 µm wide, exine smooth (psilate).
Cut stems and petioles smell of anis (Pimpinella anisum L.).
The new species is named after its home country Vietnam. The provisional name “Homalomena ovatifolia” nom. ined. was used on the herbarium sheets because of its leaf shape, but has been dropped because of its easy confusion with the existing H. ovalifolia (Schott) Engl. (Engler 1912).
2n = 38; counted in root tip mitoses of plants cultivated in the Botanic Garden Munich, from the same wild source as the holotype.
Distribution and ecology
Homalomena vietnamensis is so far known from the southern North Central Coast (Bac Trung Bo) region (province Thua Thien-Hue) and the South Central Coast (Nam Trung Bo) region (provinces of Quang Nam and Khanh Hoa) of Vietnam. The species grows in the evergreen forest on the floor with leaf litter in deep shade. In cultivation the plants flowered in December, January, April and May.
Additional specimens seen
VIETNAM: THUA THIEN HUE: Phu Loc – Bach Ma, 26.4.1939 (flowering), E. Poilane 29756 (P). – KHANH HOA: Go Oi, 1939, Poilane 3155 (P). – QUANG NAM: Between Lang Moi and Mang Tra, 1939, Poilane 31748 (P); Tra Mi, 1939, Poilane 31591 (P).
All known species of Homalomena from Vietnam (as well as from Laos, Cambodia and southern China) have ovate leaf blades with a cordate base, except H. pierreana Engl.from N Vietnam, the leaves of which have an obtuse base as in our species but lanceolate instead of ovate blades. In this species, moreover, the single staminode of the female flowers is a very short and cylindric instead of subcylindric to slightly clavate and 1-1.1(-1.2) mm long as in our species. In the new flora of Vietnam by Hô (2000) further five species are listed: H. cochinchinensis Engl., H. gigantea Engl., H. occulta (Lour.) Schott, H. pendula (Blume) Hook. f., H. tonkinensis Engl., all with a cordate base of their leaf blades and a clavate staminode in each female flower.