AMORPHOPHALLUS LAOTICUS

PROTOLOGUE: Amorphophallus laoticus Hett., published in Aroideana 29: 62 (2006).

Amorphophallus laoticus Hett., sp. nov. Ab Amorphophallo piloso stylis longis gracilibus, inter pistillos glaber differt, ac ab Amorphophallo lanuginoso spadice pilis dispersis, polline laevi. — Type: LAOS (central), left bank of the Mekong River, Harmand s.n. (holotype, P).

SYNONYMS:

OTHER NAMES: gah buk (Lao)

DISTRIBUTION: Laos: Laos.

DISTRIBUTION NOTE: Laos: central Laos (the type, from the left bank of the Mekong), Bokeo Province (Houaysai) and Champasak Province (Khon Island, at the base of Khon Hill)².

SPECIES DESCRIPTION:

Tuber elongate, thin, to ca. 30 cm long, ca. 3 cm in diam. Leaf solitary, petiole 55-80 cm long, 1-2 cm in diam., smooth but epidermal cells distinctly sharp conical providing the petiole with a satiny sheen and a slightly papery touch, background blackish grey or dark reddish brown with many scattered, irregular, pale grey spots and numerous tiny, pale grey dots; lamina 72-100 cm wide, rachises narrowly winged throughout; leaflets elliptic-lanceolate to lanceolate, narrowly acute, 11-20 cm long, 2-4 cm wide, upper surface deep velvety green with a broad grey zone along the midrib.²

INFLORESCENCE:

Inflorescence solitary, long peduncled; peduncle 25-50 cm long, 1-1.8 cm in diam. as petiole; spathe broadly elongate triangular, acute, 10-33 cm long, 10-37 cm in diam., base and limb separated by a strong constriction, base outside pale green with scattered, linear, whitish spots, inside dark purple, limb oblique, strongly arching forward at male anthesis, outside along the centre strongly costate, colour as base but margins flushed dirty purple, inside dull dark purple, margin slightly undulate, base within strongly papillate-verrucate, verrucae often narrowly muricate or partly confluent and ridge-like. Spadix longer than spathe, sessile, 18-90 cm long; female zone cylindric, 4 cm long, 1-3 cm in diam. (incl. styles), flowers slightly distant; male zone elongate, slightly fusiform, 2.5-7.5 cm long, 1-2.8 cm in diam., flowers congested, with or without scattered hair-like staminodes in between the functional flowers; appendix elongate fusiform-conic, acute, 10-79 cm long, 0.8-2.5 cm in diam., smooth or with scattered, hair-like staminodes, glossy dark purple. Ovary depressed, lower half sunken in pocket in spadix-axis, elliptical in cross-section, 1.5-3 mm in diam., 2 mm high, base white or pale green, apex dark purple, bilocular; style long, thin, 3.5-4 mm long, 0.8-1 mm in diam., dark purple; stigma large, 2 mm in diam., 2 mm high, laterally depressed and apex depressed, very shallowly bilobed, lobes rounded, surface densely scabrate, white or dirty pale brown. Male flowers consisting of (2-)3-5 stamens; stamens 1.5 mm long; filaments 0.5 mm long, connate, whitish; anthers truncate, ca. 1.5 mm in diam., ca. 1 mm long, glossy dark purple, connective with a longitudinal groove. Staminodes hair-like, to ca. 1 cm long, dark purple. Infructescence with fruiting part cylindric, 15 cm long, 4 cm in diam., berries crowded. Berries globose or laterally depressed, ca. 1 cm long, 0.7-1 cm in diam., yellow. Pollen psilate.²

ECOLOGY:

Found in partly open, disturbed margins of degraded, mixed evergreen and deciduous seasonal hardwood forest²

PROPAGATION:

Rooting percentages ranged from 19.2% to 56.5% for cuttings taken in early September.

ETYMOLOGY:

The species epithet refers to Laos, where this species seems to be endemic.²

NOTES:

1. Amorphophallus laoticus bears a great similarity to Amorphophallus pilosus from Vietnam but differs in having a long style (only 1 mm in Amorphophallus pilosus) and having no hairs in the female zone (as opposed to numerous in Amorphophallus pilosus), and to Amorphophallus longicomus, which has a perfectly depressed-globose tuber. Other species with hairs on the spadix are Amorphophallus hirtus (Taiwan; style thick, only 1 mm long), Amorphophallus kiusianus (southern Japan, Taiwan and southeastern China; style near absent, hairs only on appendix, pollen striate-areolate), Amorphophallus henryi (Taiwan; peduncle short, hairs only on appendix) and Amorphophallus lanuginosus (Vietnam; numerous hairs only in male zone, style only 0.5 mm).²

REFERENCES:

1. Plants of the World Online, Royal Botanic Gardens, Kew — Amorphophallus laoticus Hett.

2. Aroideana 29: 62 (2006) — protologue.

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

4. Propagation of Amorphophallus by Leaf Petiole Cuttings — Juniper Level Botanic Garden