AMORPHOPHALLUS SYNANDRIFER

PROTOLOGUE: Amorphophallus synandrifer Hett. & V.D.Nguyen, published in Blumea 46: 274 (2001).

Amorphophallus synandrifer Hett. & V.D. Nguyen, spec. nov. In genere Amorphophallo unicus ob flores masculos synanthericis. Cetero Amorphophallo pygmaeo affinis, plantis triplo vel plus, stigmate duplo maiore rhombeo. - Typus: Boyce & V.D. Nguyen 1334 (holo L, spirit coll.), Vietnam, Tuy Phong, Can Na distr., Vinh Hao community, adjacent to Highway 1, 11° 20' N, 108° 52' E, alt. 5 m, in deep white quartz sand over granite, in the shelter of seasonal deciduous thorn scrub, 20 May 1998.

DISTRIBUTION: Vietnam: Vietnam.

DISTRIBUTION NOTE: Vietnam: Vinh Hao, in the Can Na district of Tuy Phong, beside Highway 1 - the only locality known.².

SPECIES DESCRIPTION:

Tuber narrowly elongate, unbranched, 10-30 cm long and to 2.5 cm across. Petiole smooth but with distinct conical epidermal cells, the background dark grey speckled brown with large irregular confluent pale grey spots bearing minute blackish dots, or the background dark brown with blackish dotting and scattered irregular or linear pale grey to whitish spots. Lamina to about 40 cm across, the rachises narrowly winged throughout; leaflets small, elliptic, to 5.5 by 2 cm, acuminate.²

INFLORESCENCE:

Inflorescence solitary and long-peduncled; peduncle as the petiole, to about 80 cm long and 8 mm across. Spathe elongate triangular, acute, erect, cymbiform, slightly fornicate, the base and limb not separated, shortly and weakly convolute and opening nearly to the base at anthesis, 15-23 cm long and 5-7 cm across, the lower margins slightly revolute; outside pale grey-green or pale grey with a darker pattern of scattered small blackish dots, inside uniformly pale grey or yellowish grey-green, the base dark purple and bearing numerous tiny irregularly elongate warts. Spadix equalling the spathe or slightly longer, sessile or substipitate, 12-23 cm long; female zone cylindrical to slightly obconic, 0.8-2 cm long and about 1.5 cm across, the flowers congested; a sterile zone between the male and female zones about 0.5 cm long; male zone elongate, subcylindric or conic, 2.5-5.5 cm long and 1.7-2 cm across at the base; appendix elongate conical, obtuse, 7-12 cm long and 1.5-2 cm across, dull grey, dull yellowish grey-green or slightly pinkish, the surface conspicuously rugulose, especially in the upper half. Ovaries depressed, oblique, oval or conspicuously diamond-shaped in cross section, about 2 mm high and 3 mm across, bright green, unilocular, the locule sitting in the acroscopic part of the ovary; style hardly separated from the ovary, thick, oblique, 1 mm long and 2-3 mm across, bright green; stigma very depressed, diamond-shaped, ellipsoid or slightly irregular in cross section, broader than the style, the margins slightly curved downward, entire or with a shortly elongate transverse depression, 0.5 mm high and 2-4 mm across, the surface nearly smooth, pale to deep yellow. Male flowers of 4 or 5 stamens, these entirely fused into a synandrium, diamond-shaped or polygonal in cross section, to 5 by 6 mm and 1-3 mm long, depressed pyramidal to pyramidal with a truncate top, the filamentous region about 2 mm long and the anther region about 1 mm long, off-white, the individual anthers sometimes partly separated by shallow ridges. Pollen indistinctly reticulate, ellipsoidal, 73 µm long. Staminodes very depressed, rhombic or polygonal in cross section, 5-6 mm across and 1-2 mm high, off-white.²

ECOLOGY:

Found in deep white quartz sand over granite, in the shelter of seasonal deciduous thorn scrub; altitude 5 m.²

ETYMOLOGY:

From synandrium, a group of stamens fused into a single body, with the Latin-fer, “bearing.” In this species the four or five stamens of each male flower are completely welded into one pyramidal block, and no other species in the genus does so throughout the male zone.²

NOTES:

1. The fused male flowers are unique in the genus, and the Latin diagnosis says so outright. Partly fused male flowers do occur elsewhere - at the very base of the male zone in Amorphophallus saururus and Amorphophallus sizemoreae - but only here do they occupy the whole of it.²

2. Where the species belongs is unresolved. Its thin tuber is shared with Amorphophallus napiger, Amorphophallus laoticus and Amorphophallus parvulus, but it differs from all of them in its very large stigmas and large flattened staminodes.²

3. The ovary has a single chamber and that chamber sits off-centre, in the acroscopic part - the side facing the top of the spadix.²

4. It grows in deep white quartz sand almost at sea level, an unusual substrate for the genus.²

REFERENCES:

1. Plants of the World Online, Royal Botanic Gardens, Kew — Amorphophallus synandrifer Hett. & V.D.Nguyen

2. Blumea 46: 274 (2001) — protologue.

3. Alan Galloway — Amorphophallus synandrifer, alangallowaybotanicals.com.