AMORPHOPHALLUS OBOVOIDEUS

PROTOLOGUE: Amorphophallus obovoideus Alderw., published in Bulletin du Jardin botanique de Buitenzorg sér. 3, 4: 164 (1922). The protologue is reproduced below.

DISTRIBUTION: Sumatera: Sumatra.

DISTRIBUTION NOTE: Sumatra: Deli - Sibolangit (now in Deli Serdang Regency, North Sumatra), where the type was gathered by J.A. Lörzing on 25 June 1918.².

SPECIES DESCRIPTION:

Translated from protologue: Petiole of the leaf...; lamina.... Cataphylls 2-3, the innermost the longest, linear-lanceolate, about 22.5 cm long. A leaf of a probably young tuber, gathered at the same locality and belonging probably to this species, is distinguished as follows: petiole about 30 cm long, slender, darker than the peduncle; lamina 3-partite; primary branches about 25 cm long, forked; pinnae (leaflets) 0-2 on each side below the fork-branches, lanceolate, 7-17 x 3.5-5.5 cm, the lowest sessile, the higher adnate with a cuneate base, the apex rather suddenly long-subcaudate-acuminate; highest leaflets binate or subbinate.²

INFLORESCENCE:

Translated from protologue: Peduncle 70-75 cm long, relatively slender, pale blue-green, adorned with large, oblong, very pale green blotches which are blue-dotted in their middle part, the upper ones often confluent and without dots, and continued onto the spathe. Spathe gradually passing from a cylindrical tube into a somewhat boat-shaped limb, 16-19 cm long, shortly acuminate at the apex and slightly recurved, outside milk-white to pale green, inside very pale; tube 2.5 cm long and 2.5 cm in diameter; limb 8 cm broad when spread. Spadix about 12.5 cm long; female inflorescence cylindrical, 1.75 cm long, 1.5 cm thick; ovaries very pale green, 1-ovuled, prismatic when dried, truncate at the apex, 4-6-angled; style almost absent; stigma capitate, pale brown; male inflorescence somewhat oblong-cylindrical, 3 cm long, 1.75 cm thick in the middle, slightly narrowed at base and apex, 1.5 cm thick, pale brown; appendix obovoid, 8 cm long, 3 cm thick, narrowed at the base, semi-hemispherical at the apex, pale yellowish, breathed over with blue-green. The dimensions are taken from the field note; in the dried material the dimensions of the inflorescences are much smaller.²

ECOLOGY:

Found in moist primeval forest; altitude: 500 m²

ETYMOLOGY:

From Latin obovoideus, “obovoid” - egg-shaped with the narrower end at the base - for the shape of the sterile appendix, which van Alderwerelt describes as obovoid, 8 cm long and 3 cm thick, tapering at the base and rounded into a half-hemisphere at the top.²

NOTES:

1. The species was described from a single gathering, and never completely: the entries for the petiole and lamina of the flowering plant were left blank in the original account, because no leaf accompanied the inflorescence. A leaf collected at the same place from what was probably a young tuber is described separately, and only tentatively assigned to the species.²

2. The measurements in the description come from the collector's field notes. The author cautions that the dried material has inflorescences very much smaller than those figures, so the dimensions given here are of the living plant.²

REFERENCES:

1. Plants of the World Online, Royal Botanic Gardens, Kew — Amorphophallus obovoideus Alderw.

2. Bulletin du Jardin botanique de Buitenzorg sér. 3, 4: 164 (1922) — protologue.