AMORPHOPHALLUS SYMONIANUS

PROTOLOGUE: Amorphophallus symonianus Hett. & Sizemore, published in Blumea 46: 273 (2001).

Amorphophallus symonianus Hett. & M. Sizemore, spec. nov. Amorphophallo yuloensi similis, folii bulbillis totis intercalaribus, tubere tuberibus lateralibus gaudenti, stigmate duplo latiore differt. - Typus: Sizemore 96-168 (L, spirit coll.), Thailand, Loei prov., east of Wang Saphung (coll. from a plant cultivated in Florida).

DISTRIBUTION: NE. Thailand: Thailand.

DISTRIBUTION NOTE: Thailand: the north-east, the type from Loei Province east of Wang Saphung, with further material from north of Petchabun.².

SPECIES DESCRIPTION:

Tuber depressed globose, to 10 cm across and about 6 cm high, brown, producing several offsets each year, these globose and not severing from the main tuber in the first season. Petiole to 105 cm long and 2.5 cm across, smooth, pale green with numerous short, narrowly linear white stripes; the joint with the lamina swells and becomes a globose or elongate intercalary bulbil, often incorporating the swollen bases of the three main rachises. Lamina to about 100 cm across, the rachises narrowly winged beyond the basal branchings, the nodes swelling and transforming entirely into globose or elliptic intercalary bulbils; leaflets elliptic to elongate elliptic, acuminate, 7-24 cm long and 4-9 cm across, the upper surface green and corrugate with strongly impressed venation, the lower surface green with strongly raised venation.²

INFLORESCENCE:

Inflorescence solitary and long-peduncled; peduncle largely or entirely hidden by the cataphylls, 10-20 cm long and 0.5-1 cm across, smooth, as the petiole. Spathe elongate oval or orbicular, sometimes broader than long, slightly concave, the top overarching the spadix, 10-13 cm long and 7-14 cm across, the base and limb not strongly differentiated, the top obtuse and the margins of the limb slightly recurved; outside pale green or flushed with pale reddish brown and bearing scattered, more or less distinct whitish dots, inside as outside but slightly less green; the base within smooth. Spadix shorter than the spathe, sessile, 8.5-12 cm long; female zone slightly obconical, 1.2-2 cm long, 0.8-1.5 cm across at the base and 1.2-2 cm at the top, the flowers congested; male zone elongate and slightly fusiform, terete or dorsoventrally compressed, 3.7-4.7 cm long and 1.7-3 cm across, the flowers congested; appendix short conical, slightly dorsoventrally compressed, 3.5-5.5 cm long and 1.6-3.5 cm across, obtuse, smooth, ivory white. Ovaries depressed-globose, slightly angulate or orbicular, 3 mm across and 2.5-3 mm high, pale green, bilocular; style conical or terete, about 1 mm long and 0.8 mm across at the base, pale green; stigma discoid and large, about 2.5 mm across and 0.5 mm high, entire, with a shallow slightly elongate central depression, the surface glossy white and smooth. Male flowers of 3-5 stamens; stamens 1.5 mm long, the filaments 0.5 mm long and free; anthers 1 mm long and about 1.5 mm across, truncate, off-white, the pores apical and shortly elongate. Pollen psilate, ellipsoidal, 71 µm long.²

PROPAGATION:

The best luck with this species was with late August cuttings, which rooted at 85.7%. By mid-September, the rooting percentage had dropped to 42.4%.

ETYMOLOGY:

Named for James R. Symon of San Francisco, who died before the species was published. His interest in the genus and his many journeys through tropical Asia produced a body of field information that fed directly into its revision.²

NOTES:

1. Every node of the leaf can swell into a bulbil, including the junction of the petiole and the lamina. These bulbils are entirely intercalary - they sit at the joints rather than on the leaf surface - and the distinction matters, because the otherwise similar Amorphophallus yuloensis of southern China has half-epiphyllar ones.²

2. From Amorphophallus yuloensis it differs further in recurved rather than slightly incurved spathe margins and a smooth rather than densely warted stigma surface. Amorphophallus yuloensis also never produces offset tubers, whereas this species makes several a year.²

3. The peduncle is almost entirely concealed by the cataphylls, so the inflorescence appears to sit on the ground.²

REFERENCES:

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

2. Blumea 46: 273 (2001) — protologue.

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

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