Geonoma lehmannii Dammer ex Burret, Bot. Jahrb. Syst. 63: 180 (1930)

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Discussion

  • Taxonomic notes: - Geonoma lehmannii is the first species dealt with here in a group of high elevation, Andean species, the G. undata clade. This group also includes G. orbignyana, G. talamancana, G. trigona, and G. undata. These species have been treated differently by both Wessels Boer (1968) and Henderson et al. (1995). They are closely related and three of them - G. lehmannii, G. orbignyana, and G. undata - are difficult to distinguish from one another, and extremely complex internally. Geonoma lehmannii differs from other species in this group, except G. talamancana, in its tubular, narrow, elongate, closely sheathing, more or less persistent prophylls and peduncular bracts which are ribbed with elongate, unbranched fibers. It differs from G. talamancana in its well-developed peduncular bract.

    Subspecific variation: - Four traits vary within this species (stem branching, stem type, leaf division, leaf plication). There is geographic discontinuity, and Central American specimens are isolated from South American ones. All Central American specimens have plicate leaves, whereas few South American specimens do. Specimens from Central America differ significantly from South American ones in eight variables (rachis width, basal pinna angle, apical pinna length, apical pinna angle, prophyll length, peduncular bract length, peduncle length, rachilla width)(t-test, P <0.05). Based on these results and geographic discontinuity, the two subgroups are recognized as subspecies (subspp. corrugata, lehmannii). (Henderson, A.J. (2011) A revision of Geonoma. Phytotaxa 17: 1-271.)A

Description

  • Plants 1.7(0.5-4.0) m tall; stems 1.1(0.1-4.0) m tall, 1.1(0.6-1.7) cm in diameter, solitary or clustered, not cane-like or cane-like; internodes 1.2(0.4-2.0) cm long, yellowish and smooth. Leaves 10(5-15) per stem, undivided or irregularly pinnate, not plicate or plicate, bases of blades running diagonally into the rachis; sheaths 15.4(7.0-24.5) cm long; petioles 23.7(1.5-72.0) cm long, drying green or yellowish; rachis 27.0(6.7-51.5) cm long, 3.5(1.4-7.6) mm in diameter; veins raised and rectangular in cross-section adaxially or not raised or slightly raised and triangular in cross-section adaxially; pinnae 3(1-9) per side of rachis; basal pinna 28.0(16.0-48.0) cm long, 2.8(0.5-11.0) cm wide, forming an angle of 35(7-77)° with the rachis; apical pinna 20.6(9.0-47.5) cm long, 7.2(1.8-20.5) cm wide, forming an angle of 22(6-39)° with the rachis. Inflorescences unbranched; prophylls and peduncular bracts ribbed with elongate, unbranched fibers, both bracts tubular, narrow, elongate, closely sheathing the peduncle, more or less persistent; prophylls 23.4(10.0-41.5) cm long, not short and asymmetrically apiculate, the surfaces not ridged, without unequally wide ridges; peduncular bracts 23.3(8.7-49.0) cm long, well-developed, inserted 17.5(4.0-39.0) cm long,; peduncles 44.5(12.5-88.5) cm long, 2.3(1.3-4.2) mm in diameter; rachillae 1, 15.5(5.5-29.0) cm long, 3.8(2.2-6.5) 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 usually spirally arranged, glabrous internally; proximal lips apiculate and lobed before anthesis, tearing in the center after anthesis, not recurved after anthesis, not hood-shaped; proximal and distal lips drying the same color as the rachillae, not joined toform 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 persistent after anthesis; staminodial tubes crenulate or shallowly lobed at the apex, those of nonfertilized pistillate flowers not projecting and persistent after anthesis. Fruits 8.1(6.6-10.7) mm long, 6.3(5.2-7.6) mm in diameter, the bases with a prominent, asymmetric stipe, the apices not conical, the surfaces not splitting at maturity, without fibers emerging, bumpy from the numerous, subepidermal, tangential, short fibers present, these coming to a point at fruit apices; locular epidermis without operculum, sculpted, usually also with a raised, meridional ridge, without pores. (Henderson, A.J. (2011) A revision of Geonoma. Phytotaxa 17: 1-271.)A