Geonoma stricta (Poiteau) Kunth (1841: 232)

Henderson, Andrew, 2011, A revision of Geonoma (Arecaceae), Phytotaxa 17, pp. 1-271 : 141-143

60. Geonoma stricta (Poiteau) Kunth (1841: 232) . Gynestum strictum Poiteau (1822: 391) . Type: FRENCH GUIANA. Without locality, no date, A. Poiteau s.n. (holotype P!).

Plants 1.8(0.4–4.0) m tall; stems 1.4(0.2–5.0) m tall, 0.7(0.3–1.6) cm in diameter, solitary or clustered, not cane-like or cane-like; internodes 3.0(0.4–8.4) cm long, yellowish and smooth. Leaves 8(4–17) per stem, undivided or irregularly pinnate, not plicate, bases of blades running diagonally into the rachis; sheaths 8.9(1.0–22.0) cm long; petioles 12.9(1.0–58.0) cm long, drying green or yellowish; rachis 29.6(10.1–75.8) cm long, 2.6(0.9–6.0) mm in diameter; veins raised and rectangular in cross-section adaxially or not raised or slightly raised and triangular in cross-section adaxially; pinnae 2(1–12) per side of rachis; basal pinna 20.4(8.0–38.0) cm long, 3.4(0.6–11.4) cm wide, forming an angle of 40(9–112)° with the rachis; apical pinna 12.6(3.2–38.5) cm long, 10.3(1.5–23.5) cm wide, forming an angle of 34(14–50)° with the rachis. Inflorescences unbranched or branched 1 order; prophylls and peduncular bracts not ribbed with elongate, unbranched fibers, flattened, deciduous or persistent; prophylls 6.8(0.7–21.3) cm long, not short and asymmetrically apiculate, the surfaces not ridged, without unequally wide ridges; peduncular bracts 0.6(0.1– 9.6) cm long, vestigial, the prophyll three times or more long, sometimes the peduncular bract apparently well-developed but then soon disintegrating, inserted 1.8(0.1–9.5) cm above the prophyll; peduncles 5.0(0.5– 17.0) cm long, 3.2(1.3–6.1) mm in diameter; rachillae 1(1–7), 12.7(1.5–37.0) cm long, 5.4(1.2–15.1) mm in diameter, the surfaces with 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 spirally arranged, glabrous internally; proximal lips without a central notch before 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 persistent or deciduous after anthesis; stamens 6; thecae diverging at anthesis, inserted onto bifid and well-developed, non-jointed connectives; 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 8.6(5.9–14.5) mm long, 5.6(4.0–7.3) mm in diameter, the bases without a prominent stipe, the apices not conical, the surfaces not splitting at maturity, without fibers emerging, ridged from the numerous, subepidermal, meridional, elongate fibers present, these coming to a point at fruit apices; locular epidermis without operculum, smooth, without pores.

Taxonomic notes:— Geonoma stricta is a member of the G. stricta clade, within which it is most closely related to G. aspidiifolia , G. oligoclona , and G. santanderensis . It differs from these three species in several character states, most obviously in its yellowish and smooth internodes. It is an extremely complicated species, treated in the past as either one species with several varieties (e.g., Henderson, 1995) or several species (e.g., Wessels Boer, 1968). Henderson and Martins (2002), in a morphometric study of this species, concluded that the varietal classification proposed by Henderson (1995) was not supported. However, these authors used only quantitative variables. With more specimens, and an analysis of both quantitative variables and qualitative traits, as well as geography, some resolution is possible, as discussed below.

Subspecific variation:— Six traits (stem branching, stem type, leaf division, adaxial veins, inflorescence branching, staminate flowers) vary within this species. For stem type, only one of 390 specimens is scored as not cane-like, and this and stem branching and leaf division are not used in the following analyses. There is no correspondence between geography and the three remaining traits (adaxial veins, inflorescence branching, staminate flowers). Geonoma stricta is widespread across the Amazon region and beyond. However, there are gaps in its distribution, and G. stricta occurs in four separate areas–the Pacific coast of Colombia (Chocó), the Central Cordillera in Colombia (Antioquia), the central and western Amazon region and adjacent sub-Andean regions, and the Guianas and adjacent Brazil (Amapá). Specimens from these four regions are analyzed separately.

There are only three specimens from the Pacific coast of Colombia (Chocó), too few to test for differences. However, these differ from the nearest other G. stricta population in the Central Cordillera in Colombia, in their shorter interbract distances (0.1–0.2 cm versus 1.2–1.3 cm) and narrower rachillae (3.1–4.5 mm versus 4.8–7.4 mm). They also occur at lower elevations, 97(50–150) m versus 852(700–1075) m. Based on these differences, and geographic separation, these specimens are recognized as a separate subspecies ( subsp. quibdoensis ).

There are only six specimens from the Central Cordillera in Colombia (Antioquia), too few to test for differences. Based on their geographic isolation, and differences from subsp. quibdoensis , they are recognized as a separate subspecies ( subsp. antioquiensis ).

In central and western Amazon regions and adjacent sub-Andean regions, Geonoma stricta is abundant, widespread, and extremely variable. In sub-Andean regions of Peru (Amazonas, Loreto, Huánuco, Pasco, Ucayali) there are specimens with branched inflorescences (these occur rarely in other areas). One subgroup of these, from Huánuco and Pasco, has leaves with raised adaxial veins, and this is recognized as a subspecies ( subsp. submontana ). The remaining specimens, with non-raised adaxial veins, can be divided into three subgroups, one from Amazonas with mostly undivided leaves and pendulous inflorescences; one from Amazonas and Loreto with pinnate leaves and erect inflorescences; and one from Huánuco, Pasco, and Ucayali with pinnate leaves and erect inflorescences. ANOVA shows that for pair wise comparison probabilities, 13 variables (stem diameter, internode length, petiole length, rachis length, rachis width, number of pinnae, basal pinna width, basal pinna angle, apical pinna width, peduncle length, peduncle width, rachilla length, rachilla width) differ significantly (P <0.05) between one pair of subgroups, and one (prophyll length) differs amongst all three subgroups. Based on these results, these three subgroups are recognized as subspecies (subspp. bracteata, divaricata, pendula).

The remaining specimens from the central and western Amazon region and eastern Andean slopes in Ecuador cannot be divided into consistent groups based on traits or geography. Adaxial veins are difficult to score in several cases; inflorescences are seldom branched, but both branched and unbranched ones can occur on the same plant; and staminate flower persistence is also difficult to score. For these reasons, these specimens are recognized as one subspecies ( subsp. arundinacea ).

In the Guianas and adjacent Brazil (Amapá) there are two subgroups of specimens, one with pinnate leaves and raised adaxial veins and the other with undivided (rarely pinnate) leaves and non-raised adaxial veins. There are only four specimens of the subgroup with pinnate leaves and raised adaxial veins, too few to test for differences. However, this subgroup is geographically isolated from the other, and the two are recognized as subspecies ( subsp. stricta , pliniana).

Key to the subspecies of Geonoma stricta

1 Pacific coast of Colombia (Chocó) and Central Cordillera in Colombia (Antioquia) ...................................................... 2

- All other areas.................................................................................................................................................................... 3

2 Pacific coast of Colombia (Chocó) ....................................................................................................... subsp. quibdoensis

- Central Cordillera in Colombia (Antioquia) ........................................................................................ subsp. antioquiensis

3 Eastern Andean slopes and central and western Amazon region...................................................................................... 4

- Northeastern Amazon region of the Guianas and Brazil (Amapá) ................................................................................... 8

4 Inflorescences unbranched or branched; central and western Amazon region, or eastern Andean slopes in Ecuador....... ......................................................................................................................................................... subsp. arundinacea

- Inflorescences branched; eastern Andean slopes in northern (Amazonas, Loreto) and central (Huánuco, Pasco, Ucayali) Peru............................................................................................................................................................................... 5

5 Leaves mostly undivided; inflorescences pendulous; Amazonas ............................................................... subsp. pendula

- Leaves pinnate; inflorescences erect; Amazonas, Huánuco, Loreto, Pasco, Ucayali ....................................................... 6

6 Veins raised and rectangular in cross-section adaxially; Huánuco, Pasco ..................................................... submontana

- Veins not raised or slightly raised and triangular in cross-section adaxially; Amazonas, Huánuco, Loreto, Pasco, Ucayali .................................................................................................................................................................................. 7

7 Amazonas, Loreto ................................................................................................................................... subsp. divaricata

- Huánuco, Pasco, Ucayali .......................................................................................................................... subsp. bracteata

8 Veins raised and rectangular in cross-section adaxially; leaves pinnate ..................................................... subsp. pliniana

- Veins not raised or slightly raised and triangular in cross-section adaxially; leaves undivided (rarely pinnate) ................ ................................................................................................................................................................... subsp. stricta