Geonoma umbraculiformis Wessels Boer (1965: 35)

Henderson, Andrew, 2011, A revision of Geonoma (Arecaceae), Phytotaxa 17, pp. 1-271 : 153-154

66. Geonoma umbraculiformis Wessels Boer (1965: 35) . Type: SURINAME. Lawa river, no date, Versteeg 322 (holotype U n.v.).

Plants 1.9(1.8–2.3) m tall; stems 1.5(0.7–2.0) m tall, 1.7 cm in diameter, cane-like; internodes 1.2 cm long, yellowish and smooth. Leaves 16(12–22) per stem, undivided or irregularly pinnate, not plicate, bases of blades recurved against the rachis; sheaths 21.0(20.0–22.0) cm long; petioles 3.8(0.0–10.5) cm long, drying green or yellowish; rachis 75.9(63.0–90.0) cm long, 5.0(3.1–7.9) mm in diameter; veins not raised or slightly raised and triangular in cross-section adaxially; pinnae 3(1–4) per side of rachis; basal pinna 45.0(40.5–51.0) cm long, 27.6(21.0–39.0) cm wide, forming an angle of 16(9–22)° with the rachis; apical pinna 31.0(15.0– 25.3) cm long, 18.3(15.5–21.5) cm wide, forming an angle of 31(28–37)° with the rachis. Inflorescences branched 1 order; prophylls and peduncular bracts not ribbed with elongate, unbranched fibers, flattened (if tubular, narrow, and elongate then not ribbed), deciduous or persistent; prophylls 13.9(13.0–15.0) cm long, not short and asymmetrically apiculate, the surfaces not ridged, without unequally wide ridges; peduncular bracts 28.8(23.0–34.5) cm long, well-developed, inserted 4.4(3.0–5.7) cm above the prophyll; peduncles 35.4(31.0–40.5) cm long, 3.9(2.5–5.0) mm in diameter; rachillae 4(3–6), 17.4(12.0–23.5) cm long, 3.3(2.7– 4.2) mm in diameter, the surfaces without spiky, fibrous projections or ridges, drying brown or yellow-brown, without short, transverse ridges, not filiform and not narrowed between the flower pits; flower pits spirally arranged, glabrous internally; proximal lips with a central notch before anthesis, often the two sides of the notch overlapping, not recurved after anthesis, not hood-shaped; proximal and distal lips drying the same color as the rachillae, not joined to form a raised cupule, the proximal lip margins overlapping the distal lip margins; distal lips well-developed; staminate and pistillate petals not emergent, not valvate throughout; staminate flowers deciduous after anthesis; stamens 6; thecae diverging at anthesis, inserted directly onto apiculate filament apices; anthers not short and curled at anthesis, usually elongate, spiraled and twisted or sometimes remaining straight; non-fertilized pistillate flowers deciduous after anthesis; staminodial tubes lobed at the apex, the lobes spreading at anthesis, acuminate, those of non-fertilized pistillate flowers not projecting and persistent after anthesis; fruits 12.6(12.0–13.0) mm long, 10.3(9.7–11.0) mm in diameter, the bases without a prominent stipe, the surfaces not splitting at maturity, without fibers emerging, not bumpy, not apiculate; locular epidermis with operculum, smooth, with pores.

Distribution and habitat:— From 1°50’S– 5°29’N and 46°10’– 58°23’W in the eastern Amazon region in Guyana, French Guiana, and Brazil at 549(200–750) m elevation in lowland rainforest ( Fig. 41 ).

Taxonomic notes:— Wessels Boer (1968) included Geonoma umbraculiformis as a synonym under G. triglochin . The two are closely related but G. umbraculiformis differs from G. triglochin in its fruits surfaces which do not split at maturity. The two species are also widely separate geographically, with G. triglochin occurring in the western Amazon region in Colombia, Ecuador, and Peru.

Subspecific variation:— Only one trait (leaf division) varies within this species. Specimens come from scattered areas, but the gaps are likely to be artifacts of insufficient collecting.

Figures

FIGURE 41. Distribution maps of Geonoma triandra, G. triglochin, G. trigona, and G. umbraculiformis.