AMORPHOPHALLUS TAUROSTIGMA
PROTOLOGUE: Amorphophallus taurostigma Ittenb., Hett. & Bogner, published in Botanische Jahrbücher für Systematik 121: 12 (1999).
4. Amorphophallus taurostigma Ittenbach, Hetterscheid & Bogner, spec. nov. Type: Madagascar, Montagne des Français, Hetterscheid H.AM.023-T (L, holo, inflor. in FAA), cult. in Leiden Bot. Gard., Bonn Bot. Garden, and Munich Bot. Garden; orig. coll. Bogner 166 (dried material of this coll. in B, K, M). Differt ab Amorphophallus hildebrandtii stigmate profunde lobato, lateraliter compresso et spadice spatham excedenti.
DISTRIBUTION: N. & W. Madagascar: Madagascar.
DISTRIBUTION NOTE: Madagascar: endemic to the island and widespread in the west and north - the type came from the Montagne des Français in the far north, with further gatherings from Tulear, the Morombe district, the Tsingy de Bemaraha, Maevatanana, Majunga and Betioky.².
SPECIES DESCRIPTION:
Tuber depressed-globose to disc-shaped, to about 20 cm across, pale brown, developing long rhizomatous offsets each season with a thickened top, these often loosening as the rhizomatous part rots away. Leaf solitary, developing after flowering in the same season; petiole 60-130 cm long and 3-6 cm across, smooth, the background pale grey and covered with numerous distinct or indistinct, partly confluent, circular pale brown spots often edged dark brown. Lamina to about 180 cm across, highly dissected; leaflets ovate, elliptic-lanceolate or lanceolate, long acuminate, 1-26 cm long and 1-6 cm across, the upper surface green with a distinct pinkish and whitish margin at the base.²
INFLORESCENCE:
Inflorescence long-peduncled; peduncle 50-110 cm long and 2.5-3 cm across, coloured as the petiole. Spathe 22-50 cm long and about 15-30 cm across, with only a very shallow constriction between limb and base on the dorsal side; outside the base is pale greyish brown with minute white dots but largely covered by numerous confluent rounded spots, these bright pale green and usually dark-green-edged, turning entirely dark green upwards; outside the limb pale purplish with a dense pattern of dot-like dirty whitish-greenish marks, flushed dirty green near the margin and with dirty pale greyish-greenish rounded spots in the centre, the limb strongly folded lengthwise and somewhat spiralling; inside the limb dirty purplish brown with faint dark green spots and dark green veins, dark brown towards the margin; inside the base with broad, strong, branching and interconnecting ridges, dirty purplish brown, the upper half dirty whitish and pale brownish with rounded, partly confluent pale green spots edged darker green and filled with whitish green dots, turning entirely dark green upwards. Spadix sessile, 30-68 cm long, longer than the spathe; female zone cylindric, 1.5-5 cm long and 2-2.5 cm across, the flowers distant; male zone cylindric to obconic, 2.5-6 cm long and 2-3.5 cm across, the flowers congested; appendix elongate fusiform, 26-60 cm long and 2-4 cm across at its broadest, smooth but shallowly grooved at the base, the apex narrowly obtuse, dirty olive-green and slightly paler and brighter upwards. Ovaries slightly elongate, laterally compressed, ovate to rounded in cross section, 2-3 mm long and 1.3-2 mm across, the base bright green and the upper part blackish, one-chambered or incompletely two-chambered with a septum developed only weakly in the upper half, with one or two ovules; style conic and suddenly narrowed at the middle, 1-1.5 mm long, 1.2 mm across at the base and 0.6-0.8 mm at the top, blackish with the base flushed green; stigma strongly and deeply two- or three-lobed and laterally compressed. rounded in cross section, 1.5 mm long and 1.8 mm across at the base, pale whitish green turning dirty yellowish-orange, the lobes strongly diverging, narrowly conic and acute, the surface strongly warted though the top is sometimes without stylar tissue. Male flowers of 3 to 5 stamens; stamens 1.5-3 mm long; filaments 0.5-1.5 mm long, connate at the base; anthers 1-1.5 mm long and 1 mm across, truncate, off-white, the connective olive green turning brown and slightly raised, the pores elongate and curved. Pollen inaperturate, ellipsoid, the exine fossulate. Berries ovoid, 0.7-1 cm long and 0.5-0.6 cm across, with one or occasionally two seeds.²
ECOLOGY:
Prefers shady humus pockets between or on rocks, from 10 to 600 m, on soils with a pH of 5.4-5.8. It flowers at the onset of the rainy season, in September and October, and fruiting begins in December.²
ETYMOLOGY:
From Latin taurus, “bull,” and stigma. The stigma is deeply lobed and flattened from the sides, and the authors' own caption to the plate of the spadix asks the reader to note the bullhead-shaped stigmas. It is the character the species was separated on.²
NOTES:
1. The species was cut out of Amorphophallus hildebrandtii, under which name mainland Madagascan plants had long been passing. It differs from it in the deeply lobed, laterally compressed stigma and in a spadix that exceeds the spathe.²
2. Amorphophallus hildebrandtii itself proved to be a plant of the island of Nosy Be rather than of the mainland, and the mainland material was split into this species and Amorphophallus ankarana in the same paper.⁵
3. No specimen has ever been collected that matches the holotype of Amorphophallus hildebrandtii: every gathering with a spathe coloured like it has a spadix much longer than the spathe.²
4. It belongs to a group of northern Madagascan species that also holds Amorphophallus erythrorrhachis, Amorphophallus andranogidroensis and Amorphophallus perrieri. Molecular work leaves the relationships among the first three unresolved, and they are morphologically very close; what separates them is the number of chambers in the ovary and the shape and size of the appendix.⁵
5. The ovary is one-chambered or only incompletely two-chambered, with the septum weakly developed in the upper half alone, and carries one or two ovules.²
6. The leaf appears after flowering in the same season, and can reach 1.8 m across.²
7. It is a common plant, not a rarity: the account calls it a common species and lists gatherings from Tulear, the Morombe district around Lake Ihotry, Ankazoaba, the Tsingy de Bemaraha, Besafotra near Maevatanana, Majunga and the Beza Mahafaly reserve near Betioky, besides the type gathering in the far north.²
8. The boiled tubers are eaten by the Sakalava.²
REFERENCES:
1. Plants of the World Online, Royal Botanic Gardens, Kew — Amorphophallus taurostigma Ittenb., Hett. & Bogner
2. Botanische Jahrbücher für Systematik 121: 12 (1999) — protologue.
3. Alan Galloway — Amorphophallus taurostigma, alangallowaybotanicals.com.