AMORPHOPHALLUS LUNATUS

PROTOLOGUE: Amorphophallus lunatus Hett. & Sizemore, published in Aroideana 29: 64 (2006).

Amorphophallus lunatus Hett. & M. Sizemore, sp. nov. Amorphophallo saururo similissimus, sed laminae multo minore divisae, stylus brevissimus. Etiam Amorphophallus sizemoreae similis, sed in ovario biloculare nec uniloculare differt. — Type: from a plant cultivated in the Botanical Gardens of Wageningen University (orig. coll. THAILAND, Kanchanaburi Province, road from Kanchanaburi to Thung Hi, "in medium shade in soil on right slope in secondary growth", M. Sizemore), 17 February 2004, Hetterscheid H.AM.1358-T (holotype, WAG, spirit collection).

DISTRIBUTION: Thailand: Thailand.

DISTRIBUTION NOTE: Thailand: Kanchanaburi and Nakhon Sawan Provinces².

SPECIES DESCRIPTION:

Tuber short elongate, rarely branching, to 8 cm long, to 3 cm in diam. Leaf solitary; petiole terete, 25-30 cm long, 7-8 mm in diam., uniformly pale reddish brown; lamina 17-20 cm in diam., main segments with few, relatively large leaflets, winged to the base. Leaflets elliptic-oblong, 6-11 cm long, 2.8-4.5 cm in diam., acute-acuminate, upper surface rich dark green, margin narrowly lined purplish-red, lower surface pale green, margin as upper surface.²

INFLORESCENCE:

Inflorescence solitary; peduncle 20 cm long, 5 mm in diam., as petiole; spathe ovate, slightly concave, erect, 6 cm long, 4 cm in diam., greenish white all over, margins involute, apex acute, base within densely clothed with short, fleshy, complexly-branched verrucae. Spadix sessile, longer than spathe, 11.5 cm; female zone cylindric, 0.5 cm long, 0.7 cm in diam., flowers adjacent, not densely congested; male zone cylindric-conic, base slightly constricted, 3 cm long, 0.6 cm in diam. at the base, 0.5 cm at the apex, flowers congested; appendix 8 cm long, ca. 0.7 cm in diam., narrowly elongate conical, tapering from base to apex, laterally flattened, base slightly attenuate, apex narrowly obtuse, surface irregularly rugulose, pale yellowish green, emitting a strong smell of gas (oligomethyl-oligosulphides). Ovaries strongly depressed, 2.5-3 mm in diam., 1 mm high, pale green, bilocular; style 0.4 mm long, 1.5 mm in diam., white; stigma disciform, 2 mm in diam., 0.3 mm high, subentire to shallowly 4-5-lobed, grooves between lobes radiating from the centre, central depression slightly elongate, margin sometimes slightly notched and lobed-sinuous, surface minutely rugulose, white. Male flowers consisting of 2-5 stamens; stamens 1 mm high, 1-1.5 mm in diam., polygonal in cross-section; filaments ca. 0.5 mm long, fused, whitish; anthers ca. 0.5 mm long, truncated or slightly conical, pale greenish, pores apical, rounded or in the lowermost lunate to circular. Pollen striate.²

ECOLOGY:

Found in medium shade in secondary growth²

ETYMOLOGY:

The species is named for the shape of the pores in the lower male flowers, which are lunate — crescent-shaped.²

NOTES:

1. The inflorescence of Amorphophallus lunatus resembles that of Amorphophallus saururus, but the style is much shorter. From Amorphophallus sizemoreae it differs in a much smaller inflorescence, smaller leaf and bilocular ovary (vs. unilocular). The typical shape of the pores in the lower male flowers is shared with Amorphophallus operculatus.²

REFERENCES:

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

2. Aroideana 29: 64 (2006) — protologue.

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