Geonoma orbignyana Martius 1843
Creators: name: Henderson, Andrew
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Arecales
Arecaceae
Geonoma
Geonoma orbignyana

description: 45. Geonoma orbignyana Martius (1843: 22). Type: BOLIVIA. Cochabamba: Yuracares, no date, A. d’Orbigny 44 (holotype P n.v.).
Plants 2.0(0.5–7.0) m tall; stems 1.5(0.1–4.0) m tall, 1.2(0.5–2.2) cm in diameter, solitary or clustered, not cane-like or cane-like; internodes 1.0(0.2–3.8) cm long, yellowish and smooth, or, if short and congested, not scaly. Leaves 10(4–20) per stem, undivided or irregularly pinnate, sometimes regularly pinnate and the pinnae with 1 main vein only, not plicate or plicate, bases of blades running diagonally into the rachis; sheaths 18.5(5.0–60.0) cm long; petioles 30.0(1.5–90.0) cm long, drying green or yellowish; rachis 32.7(5.0–76.0) cm long 3.5(1.2–8.2) mm in diameter; veins raised and rectangular in cross-section adaxially; pinnae 5(1–26) per side of rachis; basal pinna 30.1(13.0–59.5) cm, long, 3.0(0.1–15.5) cm wide, forming an angle of 44(7–95)° with the rachis; apical pinna 20.6(7.7–47.5) cm long, 7.1(0.3–21.3) cm wide, forming an angle of 25(6–43)° with the rachis. Inflorescences unbranched or branched 1–2 orders; prophylls and peduncular bracts not ribbed with elongate, unbranched fibers, flattened (if tubular, narrow, and elongate then not ribbed), deciduous or persistent; prophylls 21.2(3.4–41.5) cm long, not short and asymmetrically apiculate, the surfaces not ridged, without unequally wide ridges; peduncular bracts 19.5(3.0–49.0) cm long, well-developed, inserted 9.8(0.8– 39.0) cm above the prophyll; peduncles 30.9(6.0–88.5) cm long, 3.5(1.3–11.1) mm in diameter; rachillae 5(1– 28), 15.3(5.0–31.0) cm long, 3.5(1.8–6.6) 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, sometimes decussately or tricussately, then the groups not closely spaced nor consistently arranged throughout the rachillae, 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 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 persistent after anthesis; staminodial tubes crenulate or shallowly lobed at the apex, those of non-fertilized pistillate flowers not projecting and persistent after anthesis; fruits 9.0(6.0–16.5) mm long, 6.8(5.1–12.9) 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, smooth, without pores.
Taxonomic notes:— Geonoma orbignyana is a member of a group of high elevation, Andean species, the G. undata clade, which also includes G. lehmannii, 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 orbignyana differs from G. lehmannii and G. talamancana in its prophylls and peduncular bracts which are flattened and not ribbed with elongate, unbranched fibers; from G. talamancana in its well-developed peduncular bract; from G. trigona in its welldeveloped distal lips; and from G. undata in its prophyll surfaces which are not ridged and without unequally wide ridges.
Geonoma jussieuana is treated here as a synonym of G. orbignyana subsp. orbignyana (contra both Wessels Boer, 1968 and Henderson et al., 1995). The type specimen, with its unbranched inflorescence, comes from a Bolivian population of plants with both unbranched and branched inflorescences (sometimes on the same specimen). In bract structure specimens of this population resemble others of G. orbignyana. Geonoma lehmannii subsp. lehmannii, superficially similar to this population in its unbranched inflorescences, does not reach Bolivia and has its southernmost population in central Peru.
Subspecific variation:— Five traits vary within this species (stem branching, stem type, leaf division, leaf plication, inflorescence branching). Excluding stem branching and leaf division and one trait for which there are few data (stem type), the state distributions of the remaining two traits (leaf plication, inflorescence branching) do not divide the specimens into consistent subgroups which are geographically separated. Both leaf plication and inflorescence branching appear inconsistent. Leaf plication is difficult to score in this species, and branched and unbranched inflorescences can be found on the same specimen. There is, however, geographic disjunction and there is a gap in eastern Panama between Central American and South American specimens.
Central American specimens differ from South American ones in 12 variables (rachis width, number of pinnae, basal pinna length, basal pinna width, basal pinna angle, apical pinna length, apical pinna width, apical pinna angle, peduncular bract length, interbract distance, peduncle length, number of rachillae)(t -test, P <0.05). Based on this and geographic separation, the two subgroups are recognized as subspecies (subspp. hoffmanniana, orbignyana).
Key to the subspecies of G. orbignyana
1 Peduncles 25.6(6.0–59.5) cm long; South America (Venezuela, Colombia, Ecuador, Peru, and Bolivia) .................... .......................................................................................................................................................... subsp. orbignyana
- Peduncles 32.4(20.9–56.0) cm long; Central America (Nicaragua, Costa Rica, Panama)............ subsp. hoffmanniana
description: Published as part of Henderson, Andrew, 2011, A revision of Geonoma (Arecaceae), pp. 1-271 in Phytotaxa 17 on pages 110-111, DOI: 10.11646/phytotaxa.17.1, http://zenodo.org/record/3538362