Volume 11 > Part 2 > Year 2012 > Page 138 > Araceae > Amorphophallus

4. Amorphophallus asterostigmatus Bogner & Hett.

Blumea 36: 467. 1992.

Accepted Name : This is currently accepted.

Description : Tuber depressed-globose or irregular, 3–5 by 5–9 cm, with few or several short, elongate or subglobose offsets. Leaf solitary; petiole 60–70 by 1–1.8 cm, smooth, silvery greyish reddish to greenish with scattered, suborbicular or elliptic, dark chocolate-brown spots; leaf blade 50–100 cm diam.; leaflets more or less elliptic, 6–19 by 2–4.7 cm, long decurrent on the rachis, base cuneate, apex acuminate, adaxially dark green, abaxially paler, rachis and abaxial surface of main veins coloured as petiole, main vein very strong, primary and secondary lateral veins not prominent, 2–3 mm distant, inner collecting vein ca 2–3 mm distant from the margin. Inflorescence preceded by four membranous cataphylls, 4–25 cm long; peduncle 35–70 by 1.3–2 cm, greenish to greyish mauve with a few very dark brown spots; spathe erect, elongate ovate, as long as or longer than spadix, base convolute, 15–21 by 7–13 cm, apex more or less cuspidate-apiculate, with a ca 3 mm long tip, exterior margin greenish, with a faint, pale purplish or reddish brown tinge near the middle, interior cream or pale green, the base greenish and with or without irregular, pale purplish flushes, base within smooth; spadix sessile or subsessile (lowermost 1.5–3 mm devoid of flowers), 11–17.5 cm long; pistillate flower zone 1–2.8 by 1.5–1.7 cm; ovaries ca 4 mm long; ovary depressed-globose, 3.5–5 by 2–2.5 mm, pale green; style curved towards the spadix apex, elongate-conical, 1.5–3 by ca 1.5 mm at the base, ca 1 mm at apex, golden yellow or pale dirty yellowish; stigma large, deeply 2– to 4-lobed, irregularly star-shaped in upper view, margin strongly sinuous and undulate, 2 by 2.5–3 mm, echinate-scabrate, dirty yellowish; staminate flower zone cylindrical or slightly conical, 2.7–5 by 1.3–1.5 cm; staminate flowers 2–5-androus, entirely yellowish or with a reddish tinge at the apex; stamens broadly elliptic-oblong, conical after anthesis, ca 3 by 1–1.2 mm; filaments 2 mm long, lower half connate; anthers ca 1 mm long; thecae with a slit-like apical or subapical pore; appendix elongate-conical with a rounded apex, 6–11.5 by 1.3–1.5 cm, smooth, yellowish to cream-coloured, basal 1.5–2 cm with conspicuous, irregularly elongate-rhombic, flat, sterile staminodes, 3–10 by 2–5 mm. Fruit not seen.

Thailand : CENTRAL: Lop Buri, Saraburi.

Distribution : Endemic. The type (J.BOGNER 2096, holotype L, isotypes K, M) was purchased from the flower-market in Bangkok.

Ecology : On slopes with limestone boulders.

Vernacular : Buk kan yao (บุกก้านยาว)(Lop Buri).

Notes: The inflorescence of Amorphophallus asterostigmatus is most similar to A. longituberosus but the latter has 2-, 3-, or 4-locular ovaries, lateral pores and a 2-, 3-, or 4-lobed stigma. Another conspicuous difference between these species is the shape of the tuber, which is depressed-globose in A. asterostigmatus but elongate in A. longituberosus.

In the uppermost staminate flowers, the anthers are irregularly to entirely fused and, in some flowers, a number of thecae are absent, resulting in structures intermediate between staminate flowers and staminodes. Apparently, the staminodes represent entire staminate flowers with only a lack of differentiation of thecae. Since the intermediate flowers are synandriate, the staminodes should be regarded as synandrodia.