Geonoma laxiflora Martius (1823: 12)

Henderson, Andrew, 2011, A revision of Geonoma (Arecaceae), Phytotaxa 17, pp. 1-271 : 84-85

31. Geonoma laxiflora Martius (1823: 12) . Lectotype (designated by Wessels Boer 1968): BRAZIL.

Amazonas: Rio Japurá, no date, C. Martius s.n. (lectotype M!).

Geonoma laxiflora var. depauperata Trail (1876: 326) . Type: BRAZIL. Amazonas: Ananaá, N bank of Rio Solimões, 6 September 1874, J. Trail 1024/CXVI (holotype K!).

Plants 3.5(2.0–5.0) m tall; stems 3.0(1.9–4.0) m tall, 0.8(0.6–1.3) cm in diameter, clustered, cane-like; internodes 1.7(1.0–3.0) cm long, yellowish and smooth. Leaves 7(5–10) per stem, undivided or rarely irregularly pinnate, not plicate, bases of blades running diagonally into the rachis; sheaths 7.3(5.0–10.0) cm long; petioles 9.1(4.0–13.5) cm long, drying green or yellowish; rachis 20.6(11.5–31.5) cm long, 2.9(1.1–4.6) 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 of 27(14–35)° with the rachis; apical pinna 22.0(13.0–31.5) cm long, width not applicable, forming an angle of 23(18–31)°. Inflorescences branched 1–2 orders; prophylls and peduncular bracts not ribbed with elongate, unbranched fibers, flattened, deciduous; prophylls 3.9(2.3–5.3) cm long, short, asymmetrically apiculate, the margins curved around the stem, the surfaces flat with dense, felty, brown tomentum, prophyll equal to and early deciduous with the peduncular bract, the surfaces not ridged, without unequally wide ridges; peduncular bracts 1.7(1.0–3.0) cm long, well-developed, inserted 0.2(0.1–0.4) cm above the prophyll; peduncles 3.8(2.2–5.5) cm long, 3.0(1.5– 5.4) mm in diameter; rachillae 7(3–12), 24.2(9.7–31.0) cm long, 1.8(1.0–2.9) 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 usually spirally arranged, sometimes decussately or tricussately, then the groups not closely spaced nor consistently arranged throughout the rachillae, glabrous internally; proximal lips without a central notch before anthesis, not recurved after anthesis, hood-shaped at anthesis, sometimes splitting post-anthesis; 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; staminodial tubes of non-fertilized pistillate flowers not projecting and persistent after anthesis; fruits 7.8(5.8–9.0) mm long, 6.6(5.7–7.4) mm in diameter, the bases without a prominent stipe, the apices not conical, the surfaces not splitting at maturity, without fibers emerging, not bumpy, not apiculate; locular epidermis without operculum, smooth, without pores.

Distribution and habitat:— From 1°01’– 12°25’S and 63°33’– 76°05’W in the western Amazon region of Colombia, Brazil, Ecuador, Peru, and Bolivia at 161(80–320) m elevation usually along river margins in lowland rainforest ( Fig. 22 ).

Taxonomic notes:— This species is commonly associated with both G. leptospadix and G. deversa (e.g., Wessels Boer 1968) to which it is closely related. It differs from these in its prophyll surfaces which are flat and have dense, felty, brown tomentum.

Subspecific variation:— No trait except leaf division varies within this species. One specimen (of 34) has a pinnate leaf.

Figures

FIGURE 22. Distribution maps of Geonoma lanata, G. laxiflora, G. lehmannii subsp. lehmannii, and G. lehmannii subsp. corrugata.