Geonoma leptospadix Trail (1876: 327)

Henderson, Andrew, 2011, A revision of Geonoma (Arecaceae), Phytotaxa 17, pp. 1-271 : 88-89

33. Geonoma leptospadix Trail (1876: 327) . Type: BRAZIL. Amazonas: Tonantins, 24 November 1874, J.

Trail 963/CLXXII (holotype K!, isotypes F!, NY!, P!).

Geonoma saramaccana Bailey (1948: 104) . Type: SURINAM. Saramacca River, 9 July 1944, B. Maguire 24095 (holotype NY!).

Plants 1.5(0.5–3.0) m tall; stems 0.8(0.4–2.0) m tall, 0.7(0.5–0.9) cm in diameter, solitary or clustered, canelike; internodes 0.9(0.5–1.6) cm long, yellowish and smooth. Leaves 13(10–17) per stem, undivided or rarely irregularly pinnate, not plicate, bases of blades running diagonally into the rachis; sheaths 9.0(7.0–12.0) cm long; petioles 6.6(2.5–13.0) cm long, drying green or yellowish; rachis 32.0(21.8–43.0) cm long, 2.7(1.5–4.3) mm in diameter; veins not raised or slightly raised and triangular in cross-section adaxially; pinnae 1(1–3) per side of rachis; basal pinna length and width not applicable, forming an angle 20(10–28)° with the rachis; apical pinna 11.4(6.3–15.3) cm long, width not applicable, forming an angle of 26(20–35)° with the rachis. Inflorescences branched 1 order; prophylls and peduncular bracts not ribbed with elongate, unbranched fibers, flattened, persistent; prophylls 5.9(4.3–10.4) cm long, not short and asymmetrically apiculate, the surfaces not ridged, without unequally wide ridges; peduncular bracts 5.0(3.7–6.4) cm long, well-developed, inserted 0.9(0.3–2.3) cm above the prophyll; peduncles 13.7(6.5–20.3) cm long, 2.4(1.4–3.3) mm in diameter; rachillae 4(2–6), 13.7(6.5–28.0) cm long, 1.3(0.9–1.8) mm in diameter, the surfaces without spiky, fibrous projections or ridges, drying brown, with faint to pronounced, short, transverse ridges, not filiform and not narrowed between the flower pits; flower pits spirally arranged, glabrous internally; proximal lips without a central notch before anthesis, not recurved after anthesis, hood-shaped at anthesis, sometimes splitting postanthesis; 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 almost directly onto the filament apices, the connectives bifid but scarcely developed; anthers short and curled over at anthesis; non-fertilized pistillate flowers deciduous after anthesis; staminodial tubes crenulate or shallowly lobed at the apex, when lobed the lobes not spreading at anthesis nor acuminate, those of non-fertilized pistillate flowers not projecting and persistent after anthesis; fruits 8.0(7.0– 9.4) mm long, 7.2(6.0–7.8) mm in diameter, the bases without a prominent stipe, the apices not conical, the surfaces not splitting at maturity, without fibers emerging, not bumpy and not apiculate; locular epidermis without operculum, smooth, without pores.

Distribution and habitat:— From 6°43’N– 13°04’S and 46°26’– 77°18’W in the Amazon region of Colombia, Venezuela, Guyana, Suriname, French Guiana, Brazil, Peru, Ecuador, and Bolivia at 361(125–850) m elevation in lowland rainforest ( Fig. 23 ).

Taxonomic notes:— Geonoma leptospadix appears similar to both G. deversa and G. laxiflora . It differs from G. deversa in its spirally arranged flower pits and from G. laxiflora in its prophylls which are not short and asymmetrically apiculate.

Subspecific variation:— No trait varies within this species except for stem branching and leaf division. One specimen (of 47) has a pinnate leaf.

There is geographical variation in this species. Regression shows there are significant associations between longitude and two stem, six leaf and four inflorescence variables. Squared multiple R for the regression of plant height on longitude is 0.15, stem diameter 0.43, petiole length 0.24, rachis length 0.37, rachis width 0.23, basal pinna angle 0.08, apical pinna length 0.29, apical pinna angle 0.25, prophyll length 0.45, peduncle length 0.43, peduncle width 0.14, and rachillae length 0.38. From east to west, plants become taller with thinner stems, petioles longer, and basal and apical angles wider. All other variables decrease and inflorescences in particular become smaller.

See under Geonoma deversa for hybrids between that species and G. leptospadix .

Figures

FIGURE 23. Distribution maps of Geonoma leptospadix and G. longipedunculata.