AMORPHOPHALLUS MYOSUROIDES

PROTOLOGUE: Amorphophallus myosuroides Hett. & A.Galloway, published in Aroideana 29: 65 (2006).

Amorphophallus myosuroides Hett. & A. Galloway sp. nov. A congeneribus facile et unice distinctus in characteribus coniunctis: rhizoma breve repens, inflorescentiae usque ad 3 cum folio maturo variegato semi-radiato simultanee producentes, appendices longae tenues, flores masculi verticillati/helicoidei, baccae corrugatae virides. — Type: from a plant cultivated by A. Galloway (orig. coll.: LAOS, Khammouane Province, A. Galloway), 26 June 2005, Galloway AGA-1756-01-T (holotype, WAG, spirit collection).

DISTRIBUTION: Laos: Laos.

DISTRIBUTION NOTE: Laos: Khammouane Province (only known from the type locality)².

SPECIES DESCRIPTION:

Underground part a very short rhizome, ca. 2 cm long, ca. 1 cm in diam., annually producing some 10-15 offsets, these fusiform, 4 mm long. Leaf solitary; petiole 18-22 cm long, 3-4 mm in diam.; lamina with very short rachises resulting in a subradiate condition, 8-10 cm across, with usually 6 leaflets; leaflets elongate elliptic, 4-5 cm long, 1 cm wide, upper surface green with a distinct broad, pale grey feathering along the midrib, acute.²

INFLORESCENCE:

Inflorescences up to 3 per season, appearing alongside the mature leaf, a few weeks after leaf development, each ca. 4 weeks apart; peduncle 16-22 cm long, 2-3 mm in diam.; spathe triangular-ovate, concave, fornicate, 4-5 cm long, 2.5-3 cm wide, outside white with a pale greenish lower half, inside white, base inside very shallowly verrucate with very few warts, apex acute. Spadix longer than spathe, sessile, 7.5-8.5 cm long; female zone cylindric, 6-9 mm long, 5 mm in diam., flowers more or less congested; sterile zone above female zone naked, 2-4 mm long; male zone elongate cylindric-conic, 2-2.5 cm long, 4 mm in diam. at the base, 3 mm in diam. at the apex, flowers mostly distant, partly arranged in a spiral; appendix myosuroid, 4.7-5 cm long, 2-2.5 mm in diam., slightly but distinctly sinusoid, surface smooth, off-white, apex sharply acute. Ovary depressed, 2-3-lobed, 2 mm in diam., 1 mm high, unilocular, dirty green with dark purple spots or almost entirely dark purple; style short, 0.5 mm long, dark violet-purple; stigma depressed, 0.7 mm in diam., with a central depression, surface verrucate, dark purple. Male flowers consisting of 1-3 stamens; filaments absent; anthers fused within one flower, 1 mm high, 2-3 mm in diam., off-white, pores apical, rounded. Fruiting part slightly elongate, berries congested; berries obovate, truncate, ca. 5 mm long, basal part white, upper part pale green, surface striate-verrucate. Seeds globose, ca. 3 mm in diam., pale green. Pollen striate.²

ECOLOGY:

Like the other Laotian dwarf species, found in shaded spots in small crevices shallowly filled with humus and leaf litter in limestone boulders and rock walls⁴

ETYMOLOGY:

The species epithet refers to the mouse-tail shape of the long, thin, slightly sinuous appendix.²

NOTES:

1. For its leaf alone, Amorphophallus myosuroides is unique in the genus: the subradiate condition and the pale grey feathering along the midrib occur nowhere else. The inflorescence closely resembles that of Amorphophallus harmandii, but that species is leafless when flowering, has distinct filaments and 2-3-locular ovaries; the short creeping rhizome instead suggests a closer affinity to Amorphophallus verticillatus.²

2. The multiple flowering behaviour — up to three inflorescences per season, produced alongside the mature leaf about four weeks apart — is shared with Amorphophallus ongsakulii.²

3. The species is a member of the Pulchellus-clade of Laotian limestone dwarfs, together with Amorphophallus claudelii, Amorphophallus ongsakulii, Amorphophallus pulchellus and Amorphophallus malkmus-husseinii.⁴

REFERENCES:

1. Plants of the World Online, Royal Botanic Gardens, Kew — Amorphophallus myosuroides Hett. & A.Galloway

2. Aroideana 29: 65 (2006) — protologue.

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

4. Another new miniature Amorphophallus (Araceae) species from Laos. Aroideana 42(1): 58-69 (2019)