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Geonoma interrupta (Ruiz & Pavon) Martius, Hist. nat. palm. 2: 8. 1823. Martinezia interrupta Ruiz & Pavon, Syst. veg. fl. peruv. chil. 296. 1798. Type. PERU. Huánuco: between Pozuzo and Cuchero, Nov 1820, J. Pavon s. n. (holotype: MA, holotype image!; isotypes: K! M! MO! F neg. 18509).

Plant height 3.9(1.0-8.0) m, CV 0.4, n = 62; stems solitary; stem diameter 5.1(1.8-15.0) cm, CV 0.5, n = 34; number of leaves per stem 13(8-24), CV 0.3, n = 17. Leaves irregularly pinnate with multi-veined pinnae, sometimes intermixed with 1-veined pinnae; petiole length 64.8(11.5-110.0) cm, CV 0.4, n = 21; rachis length 132.6(26.4-200.0) cm, CV 0.3, n = 22; rachis width 8.9(3.3-16.0) mm, CV 0.3, n = 50; number of leaf divisions per side of rachis 17(2-47), CV 0.8, n = 29; basal angle of pinna divergence 46(25-60)°, CV 0.2, n = 49; basal pinna width 6.1(0.8-27.0) cm, CV 0.9, n = 48; apical angle of pinna divergence 31(15-40)° CV 0.1, n = 43; apical pinna width 22.5(10.0-39.05) cm, CV 0.3, n = 44. Inflorescences horizontal or pendulous and infrafoliar or less often interfoliar; prophyll length 21.4(13.5-40.0) cm, CV 0.3, n = 20; peduncular bract length 19.3(14.0-25.5) cm, CV 0.2, n = 8; distance between bract scars 3.9(0.3-7.5) cm, CV 0.5, n = 30; peduncle length 23.6(6.5-34.0) cm, CV 0.3, n = 35; peduncle width 13.8(3.5-20.1) mm, CV 0.3, n = 27; orders of inflorescence branching 2-4, n = 17; rachilla length 19.3(5.5-29.7) CV 0.2, n = 125; rachilla width 2.3(1.3-3.4) mm, CV 0.2, n = 123; number of rachillae no data; rachillae tending to collapse between the pits on drying, the pits longer than wide; pistillate flowers mostly falling after anthesis (if not developing into fruits), the empty pits and proximal lips becoming narrowed; proximal lip of pit not hairy internally, or only along the margins, rarely pits hairy proximally and distally internally; rachillae hairs to 0.1 mm long, at least some branched; fruit diameter 4.6(3.9-6.3) mm, CV 0.1, n = 43; fruit length 5.9(4.4-7.5) mm, CV 0.1, n = 43.

Distribution. 11°53´S-18°34´N and 69°16´-95°06´W at a mean elevation of 434 (0-1540) m in Mexico, Guatemala, Belize, Honduras, Nicaragua, Costa Rica, Panama, Colombia, Venezuela, Ecuador, and Peru.

There is a gap between Central American and Andean specimens. There are significant differences in five quantitative variables (stem diameter, leaf number, number of leaf divisions, prophyll length, fruit diameter) between specimens from these two regions (t-test, P <0.01). Central American specimens are larger in all variables except fruit diameter, and occur at a lower mean elevation (318 m) than Andean specimens (616 m). These two are therefore recognized as geographic subgroups (i.e., subspecies).

Key to the subspecies of Geonoma interrupta

1a. Number of leaf divisions per side of rachis 29(12-47); Mexico, Guatemala, Belize, Honduras, Nicaragua, Costa Rica, Panama, and just reaching northwestern Colombia..... G. interrupta subsp. magnifica.
1b. Number of leaf divisions per side of rachis 11(2-38); Colombia, Venezuela, Ecuador, and Peru.....G. interrupta subsp. interrupta.

Geonoma interrupta subsp. interrupta

Geonoma purdieana Spruce, J. Linn. Soc., Bot. 11: 109. 1871. Type. COLOMBIA. La Guajira: Río de la Hacha, Dec 1844, W. Purdie 259 (holotype: K!).

Geonoma dryanderae Burret, Notizbl. Bot. Gart. Berlin-Dahlem 12: 615. 1935. Type. COLOMBIA. Valle: Central Cordillera, Río Tulua, 1200 m, June 1935, J. Dryander 30 (holotype: B; holotype image!).

Stem diameter 4.0(1.8-6.0) cm, CV 0.3, n = 19; number of leaves per stem 11(8-16), CV 0.2, n = 12; number of leaf divisions per side of rachis 11(2-38), CV 0.8, n = 20; prophyll length 16.6(13.5-20.0) cm, CV 0.1, n = 7; fruit diameter 4.8(4.0-6.3) mm, CV 0.1, n = 16; fruit length 6.1(4.8-7.5) mm, CV 0.1, n = 16.

Distribution. Forty specimens from 11°53´S-11°05´N and 69°16´-79°28´W at a mean elevation of 586 (20-1540) m in Colombia, Venezuela, Ecuador, and Peru (map).

There is clinal variation in this subgroup. Multiple regression shows there are significant (P <0.01) associations between elevation and three leaf and four inflorescence variables. Squared multiple R for the regression of basal pinna length on elevation is 0.49, apical pinna length 0.46, apical pinna angle 0.50, peduncle length 0.71, peduncle width 0.66, distance between bracts 0.77, and rachilla length 0.23. Leaf shape changes with increasing elevation, and basal and apical pinna length become shorter, and apical pinna angle becomes wider. Peduncles become shorter and narrower, distance between bracts and rachilla length less, with increasing elevation.

An extreme instance of this clinal variation is seen in two specimens, from high elevations (1400-1540 m) on the Serranía de la Macarena in Colombia (#78, 471)(determined by Wessels Boer as Geonoma euspatha). They are the smallest of all specimens examined in this subspecies.

Geonoma interrupta subsp. magnifica Henderson, stat. nov. Geonoma magnifica Linden & H. Wendland, Linnaea 28: 335. 1856. Type. MEXICO. Tabasco: between San Carlos and Macsupana, no date, A. Ghiesbreght s. n. (holotype: GOET)

Stem diameter 6.5(2.5-15.0) cm, CV 0.4, n = 15; number of leaves per stem 17(8-24), CV 0.4, n = 5; number of leaf divisions per side of rachis 29(12-47), CV 0.4, n = 9; prophyll length 24.0(17.5-40.0) cm, CV 0.2, n = 13; fruit diameter 4.5(3.9-5.1) mm, CV 0.1, n = 27; fruit length 5.7(4.8-7.5) mm, CV 0.1, n = 16.

Distribution. Ninety-eight specimens from 7°18´-18°34´N and 76°45´-95°06´W at a mean elevation of 320 (0-1500) m in Mexico, Belize, Guatemala, Honduras, Nicaragua, Costa Rica, and Panama and just reaching northwestern Colombia (map). There is no evidence of clinal variation in this group.