AMORPHOPHALLUS ONCOPHYLLUS
PROTOLOGUE: Amorphophallus oncophyllus Prain ex Hook.f., published in The Flora of British India 6: 516 (1893).
Amorphophallus oncophyllus, Prain mss.; spathe long-peduncled tube ovoid dilating into a large orbicular-ovate limb the lower margins of which are revolute round the open mouth of the tube, spadix far exserted, appendage as long as the infl. elongate conoid. Andaman Islds.; on Cocos Islets, Prain.
DISTRIBUTION: Andaman Is. (Coco Is.): Andaman Islands.
DISTRIBUTION NOTE: The type was gathered by David Prain on Great Coco Island in 1889 or 1890.³ The island group lies north of the Andamans and is administered by Myanmar, although the species is listed for the Andaman Islands.
SPECIES DESCRIPTION:
Tubers sub-globose, c. 2.5-4.5 cm in diam. and 2-3 cm thick in vegetative phase; c. 7.5-9.0 cm in diam. and 4.5-6.5 cm thickness in reproductive phase; root scars annuliform. Petiole c. 52.5-96.0 cm long, dark green blotched with elongated greenish white and minute greenish white mottles in between blotches, extreme base pale purplish. Leaflets ovate-elliptic to lanceolate, 4.2-22.5 x 2.2-7.2 cm, acuminate, secondary lateral veins close; upper surface glossy green, lower surface pale green. Bulbils c. 0.6-1.5 cm in diam.³
INFLORESCENCE:
Peduncle smooth, 38-56 cm long. Spathe broader than long, broadly ovate-obtuse, c. 14-26 x 18-22 cm; basal convolute tube c. 6-7 cm long and 3.2-4.0 cm in diam., limb expanded, orbicular-ovate, c. 10 cm long with a slight constriction between tube and limb, initially erect, reflexed and horizontal at maturity, tip obtuse or broadly acute; pale greenish brown with irregular elongate greenish white blotches and dark minute spots in-between outside; inside extreme base pale pinkish, muricate, middle purplish with oblong to ovoid blotches, pale green with small green blotches at apical portion. Spadix slightly longer than spathe, exserted, c. 16.5-20.0 cm long, stipitate; stipe pale greenish, c. 0.5-1.0 cm long; female zone c. 3.5-4.0 cm long; male zone c. 4.0-4.5 cm long; appendix c. 8.0-10.5 cm long. Female flowers loosely arranged in sub-spirals, each c. 4 mm high; ovary c. 2 mm high, sub-globose, much broader than stigma, reddish, 2-locular, rarely 3-locular; style very short, c. 1.2 mm long; stigma 2-lobed, rarely 3-lobed, yellowish, c. 2.2 mm in diam. Male flowers dense, each c. 2 mm long, yellowish. Spadix-appendix fusiform or elongate-ellipsoid, pale yellowish, basal most part with slight rhomboid projections. Fruits ellipsoid, c. 1.5-1.8 cm long. Seeds 1-3, ellipsoid, c. 1.1-1.3 cm long.³
ETYMOLOGY:
From Greek onkos, “swelling” or “mass,” and phyllon, “leaf”: the leaf-bearing swellings are bulbils, borne where the rachis forks and reaching about 1.5 cm across, which drop and grow into new plants.³ Although the original description does not explicitly explain the name, it records the leaf as bulbiferous, and no other feature of the plant fits the epithet.²
NOTES:
1. Hooker called it “a superb species” and noted that his account was drawn up from a drawing, a dried specimen and a living plant at Kew rather than from field material.²
2. The species reproduces vegetatively by bulbils formed on the leaf, in addition to seed - the character its name records. In the reproductive phase the tuber roughly trebles in width, from about 2.5-4.5 cm across in a leafing plant to 7.5-9 cm in a flowering one.³
3. The limb of the spathe stands erect at first and then falls to the horizontal as the inflorescence matures.³
4. Amorphophallus oncophyllus has had an unsettled history. Hetterscheid and Ittenbach's 1996 monograph placed it in the synonymy of Amorphophallus muelleri, but it continues to be recognised as a distinct species, with a full account in the modern revision of section Conophallus, where it stands as one of the Indian endemics of that section.³
STORY:
STORY TITLE: The leaf that plants itself
In 1889 or 1890, David Prain landed on Great Coco Island - a scrap of land north of the Andamans, in what the maps now call Myanmar - and collected an Amorphophallus that nobody had named. He never published it himself. Joseph Hooker did, in the Flora of British India in 1893, crediting the name to Prain's manuscript and admitting that his account rested on a drawing, a dried specimen and a living plant at Kew rather than on anything seen growing wild. He allowed himself one flourish: a superb species.
The name Hooker took up records the strangest thing about it. Onkos is Greek for a swelling, phyllon for a leaf, and the leaf of this plant does swell: where the great forking rachis divides, it produces bulbils, hard brown knobs up to a centimetre and a half across. They ripen, drop, and grow. Matilda Smith's plate for the Botanical Magazine, published the same year, shows them plainly - two dark beads sitting in the crooks of the leaf axis, beside the huge grey spathe with its blotched crimson limb.
Since then the species has spent a century being argued over. In 1996 the standard monograph of the genus folded it into Amorphophallus muelleri and it vanished from the accepted lists. Indian botanists went on recognising it, and it now stands again as a species in its own right, treated in full in the modern revision of section Conophallus. Its tuber roughly trebles in width when the plant turns to flowering, from about four centimetres across to nine, and the limb of the spathe stands upright at first before falling slowly to the horizontal.
None of which the plant has ever needed. Every season, whatever the lists say, it drops another handful of bulbils into the leaf litter, and grows itself again.
REFERENCES:
1. Plants of the World Online, Royal Botanic Gardens, Kew — Amorphophallus oncophyllus Prain ex Hook.f.
2. The Flora of British India 6: 516 (1893) — protologue.
4. Amorphophallus oncophyllus. Curtis's Botanical Magazine 119: t. 7327 (1893)