Geonoma pinnatifrons Willd., Sp. Pl. 4: 593 (1805)

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Discussion

  • Taxonomic notes: - Geonoma pinnatifrons is a member of a group of related species characterized by its lack of a distal lip of the flower pit and flower pits hairy internally. This group, the G. interrupta clade, also includes G. euspatha, G. frontinensis, G. interrupta, and G. simplicifrons. These species have had a checkered taxonomic history. Geonoma pinnatifrons was included under G. interrupta by Wessels Boer (1965), but later reinstated (Wessels Boer, 1968). Both species are complicated internally. Geonoma pinnatifrons differs from G. euspatha, G. frontinensis, and G. simplicifrons in its prophylls surfaces which are ridged and densely tomentose with widely to closely spaced ridges, unequally wide, often dividing from and rejoining other ridges; and from G. interrupta in its flower pits which are densely hairy internally proximally and distally (see also Taxonomic notes under G. interrupta).

    Subspecific variation: - Three traits vary within this species (stem branching, stem type, locular epidermis sculpting). There are few data for any of these traits. The species occurs widely in Central America and northern South America. Six peripherally isolated areas (Lesser Antilles; Trinidad, Tobago, and the Paria Peninsula of Venezuela; Sierra Nevada de Santa Marta in Colombia; Hispaniola; Pacific coast of Colombia; Pacific coast of Mexico and Guatemala) contain subgroups that differ significantly from their nearest neighbors in four to ten variables, and these are recognized as subspecies (subspp. martinicensis, vaga, platybothros, oxycarpa, ramosissima, membranacea). The remaining specimens can be divided into three subgroups based on geography and rachis and peduncle width - northern South America (Venezuela, Colombia, and Ecuador, and just reaching Panama); eastern Panama; and the rest of Central America.
    However, there is not complete geographic separation between these. ANOVA shows that for pairwise comparison probabilities, 17 variables (plant height, stem height, leaf number, petiole length, rachis length, rachis width, number of pinnae, basal pinna length, basal pinna width, apical pinna length, apical pinna width, prophyll length, interbract distance, peduncle length, peduncle width, rachilla length, fruit diameter) differ significantly (P <0.05) between one pair of subgroups, although no variables differs amongst all subgroups. Based on this and geographic disjunction, these subgroups are recognized as subspecies (subspp. pinnatifrons, binervia, mexicana). (Henderson, A.J. (2011) A revision of Geonoma. Phytotaxa 17: 1-271.)A

Description

  • Plants 3.3(1.0-8.0) m tall; stems 2.6(0.1-6.0) m tall, 2.1(1.2-3.2) cm in diameter, solitary or clustered, not cane-like or cane-like; internodes 1.1(0.3-2.5) cm long, yellowish and smooth. Leaves 12(6-23) per stem, irregularly pinnate, not plicate, bases of blades running diagonally into the rachis; sheaths 32.5(13.0-63.0) cm long; petioles 54.9(10.0-125.0) cm long, drying green or yellowish; rachis 89.1(36.0-163.0) cm long, 6.6(1.9-14.5) mm in diameter; veins raised and rectangular in cross-section adaxially; pinnae 9(2-39) per side of rachis; basal pinna 42.3(21.5-65.0) cm long, 4.7(0.5-22.5) cm wide, forming an angle of 47(20-70)° with the rachis; apical pinna 33.6(16.0-61.0) cm long, 17.3(3.5-44.5) cm wide, forming an angle of 29(21-37)° with the rachis. Inflorescences branched 1-4 orders; prophylls and peduncular bracts not ribbed with elongate, unbranched fibers, flattened (if tubular, narrow, and elongate then not ribbed), deciduous or persistent; prophylls 15.6(7.0-25.0) cm long, not short and asymmetrically apiculate, the surfaces ridged and densely tomentose with widely to closely spaced ridges, unequally wide, often dividing from and rejoining other ridges, the prophyll margins with irregular, spine-like projections, the prophylls usually splitting irregularly between the ridges; peduncular bracts 16.8(10.0-27.5) cm long, well-developed, inserted 2.6(0.6-7.4) cm above the prophyll; peduncles 24.2(10.0-42.0) cm long, 8.1(2.4-21.2) mm in diameter; rachillae 18(4-45), 14.2(7.0-28.3) cm long, 2.3(1.1-3.8) 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, densely hairy internally proximally and distally; 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; proximal lips hood-shaped; distal lips absent; 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 or deciduous after anthesis; staminodial tubes crenulate or shallowly lobed at the apex, those of non-fertilized pistillate flowers not projecting and persistent after anthesis. Fruits 6.2(3.6-9.3) mm long, 4.8(3.5-7.0) mm in diameter, the bases without a prominent 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, smooth or locular epidermis sculpted and then usually also with a raised, meridional ridge, without pores. (Henderson, A.J. (2011) A revision of Geonoma. Phytotaxa 17: 1-271.)A