AMORPHOPHALLUS PULCHELLUS

PROTOLOGUE: Amorphophallus pulchellus Hett. & Schuit., published in Aroideana 36: 91 (2013).

Amorphophallus pulchellus Hett. & Schuit., sp. nov. Type: LAOS, Bolikhamxai Province, Lak Xao district, east of Ban Pakha, alt. 460 m, 16 May 2007, A. Schuiteman s.n. (holotype, L, spirit coll.).

DISTRIBUTION: Laos: Laos.

DISTRIBUTION NOTE: Laos: Bolikhamxai Province - Lak Xao district, east of Ban Pakha, at 460 m.².

SPECIES DESCRIPTION:

Tuber depressed globose, 0.5-1.8 cm in diam., 0.3-1.3 cm high, producing rhizomatous offsets; offsets terete, 0.5-4 cm long, 3-3.5 mm in diam. Petiole 10-16 cm long, 2-3 mm in diam., smooth, rich reddish purple or pale dirty violet, grading upwards to pale green; lamina 8-14 cm in diam., with few leaflets, to 6 or 7, rachises very short, unwinged; leaflets elliptic lanceolate, 3.5-8 cm long, 0.8-2 cm in diam., acute-acuminate, margins undulate, upper surface glossy green, lower surface slightly paler, glossy.²

INFLORESCENCE:

Inflorescences developing alongside the leaf in succession, mostly 2; peduncle 15-25 cm long, 2-2.5 mm in diam., as petiole; spathe narrowly elongate triangular, 3-3.5 cm long, 1 cm in diam. near the base, the basal 1 cm tubular with the margins fused, limb with a slightly auriculate base, erect or oblique, obtuse, outside whitish with a pinkish flush near the base, base inside smooth, dark maroon; spadix sessile, 5.5-9 cm long; female zone short cylindric, 1-1.5 mm long, 3 mm in diam., flowers congested; male zone elongate conical, 8 mm long, 2.5-3 mm in diam. at the base, 2 mm at the top, flowers slightly distant; appendix arching at the base, the upper part pendulous or semi-horizontal, 4.5-8 cm long, terete but with a slightly narrowed base, top obtuse, surface smooth, off-white. Ovaries subglobose, 2-2.5 mm in diam., 2 mm high, lobed-ribbed, unilocular, green; style absent or very short; stigma disciform, 0.7-1 mm in diam., 0.1 mm high, entire with a deep central depression, minutely verruculose. Male flowers consisting of (1-)3-5 stamens; filaments partly or entirely fused, 1 mm long, the base decurrent on the spadix axis; anthers 1 mm long, 1.5 mm in diam., pale pink, connective deep lying, upper part of the thecae separated, thecae subglobose, pores rounded, apical. The inflorescence produces a powerful sweet scent.²

ECOLOGY:

Found on forested limestone hills, in pockets of soil - mainly leaf litter - on and between the rocks; locally abundant though few plants are in flower at any time; altitude: 460 m²

ETYMOLOGY:

From Latin pulchellus, “pretty” - the diminutive of pulcher. The epithet refers to the colour contrasts between spathe, peduncle, petioles and young leaves, and the diminutive ending to the plant's small size.²

NOTES:

1. Diagnosis: its habit approaches that of Amorphophallus myosuroides of Laos, but it differs in a narrower spathe, a much longer and arching appendix, far fewer pistils, no sterile interstice between the male and female zones, longer stamens, a depressed globose tuber, rhizomatous offsets, and a very strong sweet scent where Amorphophallus myosuroides is acidic.²

2. Molecular work places it in a small monophyletic group with Amorphophallus ongsakulii and Amorphophallus myosuroides, both also from Laos. All three are dwarf plants that produce a synflorescence of one to three inflorescences alongside the leaf.²

3. A very strong sweet scent is unusual in a genus better known for carrion and dung; here it comes from an inflorescence whose spathe is barely 3 cm long.²

REFERENCES:

1. Plants of the World Online, Royal Botanic Gardens, Kew — Amorphophallus pulchellus Hett. & Schuit.

2. Aroideana 36: 91 (2013) — protologue.

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