Volume 11 > Part 2 > Year 2012 > Page 178 > Araceae > Amorphophallus

49. Amorphophallus symonianus Hett. & Sizemore

Blumea 46(2): 273. 2001.

Accepted Name : This is currently accepted.

Description : Tuber depressed globose, 2–10 by 1–6 cm, producing several annual offsets, these globose, not separating from the main tuber the first season. Leaf solitary; petiole 10–105 by 1–2.5 cm, smooth, pale green with numerous short, narrowly linear, white stripes, the joint with the leaf blade swelling and transforming into a globose or elongate intercalary bulbil, often incorporating the swollen bases of the three main rachises; leaf blade 20–100 cm diam., rachises narrowly winged distally from the basal branchings, the nodes swelling and transforming entirely into globose or elliptic intercalary bulbils; leaflets elliptic to elongate-elliptic, 7–24 by 4–9 cm, acuminate, adaxially green, corrugate, venation strongly impressed, abaxially green, venation strongly raised. Inflorescence solitary, long pedunculate; peduncle largely or entirely hidden by the cataphylls, 10–20 by 5–10 cm, smooth, appearance as petiole; spathe elongate oval or orbicular, sometimes broader than long, slightly concave, apex overarching the spadix, 9–13 by 7–14 cm, base and limb not strongly differentiated, apex obtuse, margins of limb slightly recurved, exterior pale green or flushed with pale reddish brown and with some scattered, more or less distinct whitish dots, interior as exterior, slightly less green, base within smooth; spadix shorter than spathe, sessile, 7–12 cm long; pistillate flower zone slightly obconical, 1.2–2 cm by 8–15 mm at the base, 1.2–2 cm at the apex, flowers congested; ovaries depressed-globose, slightly angular or orbicular, 3 by 2.5–3 mm high, pale green, bilocular; style conical or terete, ca 1 by 0.8 mm at the base, pale green; stigma discoid, large, ca 2.5 by 0.5 mm, entire, with a shallow, slightly elongate central depression, surface glossy white, smooth; staminate flower zone elongate, slightly fusiform, terete or dorso-ventrally compressed, 3.3–4.7 by 1.7–3 cm, flowers congested; staminate flowers 3–5-androus; stamens 1.5 mm long; filaments 0.5 mm long, free; anthers 1 by ca 1.5 mm, truncate, off-white; appendix short conical, slightly dorso-ventrally compressed, 2.7–5.5 by 1.6–3.5 cm, obtuse, smooth, ivory white. Fruit not seen.

Thailand : NORTH-EASTERN: Loei (type: Sizemore 96-168, holotype -L), Udon Thani.

Distribution : Endemic.

Ecology : In humus-filled limestone pockets, in soil on slopes, in medium shade.

Vernacular : Buk (บุก)(Loei).

Notes: Amorphophallus symonianus is similar in appearance to the S Chinese A. yuloensis H.Li, with which it shares the general shape of spathe and spadix. Amorphophallus symonianus differs in having entirely intercalary bulbils (as opposed to half-epiphyllar in A. yuloensis), recurved spathe margins (vs slightly incurved in A. yuloensis), and the stigma surface being smooth (vs densely verrucate in A. yuloensis).