Geonoma baculifera (Poit.) Kunth, Enum. Pl. 3: 233. 1841. Gynestum baculiferum Poit., Mém. Mus. Hist. Nat. 9: 389. 1822. Type. FRENCH GUIANA. Without locality, no date, A. Poiteau s. n. (holotype: P!).

Geonoma acutiflora Mart., Hist. Nat. Palm. 2: 10. 1823. Type. BRAZIL. Pará: without locality, no date, C. Martius s. n. (holotype: M; F neg. 18503).

Geonoma macrospatha Spruce, J. Linn. Soc., Bot. 11: 105. 1871. Geonoma baculifera var. macrospatha (Spruce) Drude in C. Martius, Fl. Bras.: Palmae II 3(2): 490. 1882. Type. VENEZUELA. Amazonas: Río Casiquiare, Dec 1853, R. Spruce 42 (holotype: K! isotype: P! F neg. 38652).

Plant height 2.3(0.5-6.0) m, CV 0.5, n = 58; stem height 1.6(1.0-2.5) m, CV 0.3, n = 16; stems clustered, rarely solitary; stem diameter 1.6(1.3-2.3) cm, CV 0.1, n = 24; internode length 4.0(1.4-9.3) cm, CV 0.5, n = 20; number of leaves per stem 9(6-11), CV 0.2, n = 9. Leaves irregularly pinnate with multi-veined pinnae, or undivided; sheath length 17.3(11.0-30.0) cm, CV 0.3, n = 9; petiole length 17.4(6.5-30.0) cm, CV 0.4, n = 16; rachis length 55.9(39.5-80.0) cm, CV 0.2, n = 38; rachis width 4.3(2.6-7.2) mm, CV 0.2, n = 53; number of leaf divisions per side of rachis 2(1-10), CV 0.8, n = 49; basal pinna length 54.1(42.0-72.0) cm, CV 0.2, n = 17; basal pinna width 16.9(6.7-33.0) cm, CV 0.3, n = 25; basal angle of pinna divergence 20(12-28)°, CV 0.2, n = 59; apical pinna length 28.7(14.0-39.5) cm, CV 0.2, n = 39; apical pinna width 18.7(12.5-32.5) cm, CV 0.3, n = 24; apical angle of pinna divergence 25(20-35)° CV 0.1, n = 53. Inflorescences interfoliar or rarely infrafoliar; prophyll length 23.8(12.7-33.0) cm, CV 0.3, n = 19; peduncular bract length 22.3(13.5-28.0) cm, CV 0.3, n = 5; distance between bract scars 2.9(1.3-7.0) cm, CV 0.5, n = 35; peduncle length 28.9(13.3-44.2) cm, CV 0.3, n = 53; peduncle width 4.0(2.1-8.4) mm, CV 0.3, n = 93; orders of inflorescence branching 1(1-2), CV 0.1, n = 91; rachilla length 16.7(4.0-31.0) cm, CV 0.3, n = 85; rachilla width 3.2(2.2-4.3) mm, CV 0.1, n = 92; number of rachillae 6(3-11), CV 0.2, n = 90; flower pits spirally arranged; fruit length 10.6(8.2-12.8) mm, CV 0.1, n = 37; fruit diameter 7.8(6.1-9.6) mm, CV 0.1, n = 37.

Distribution and habitat. From 7°47´S-6°50´N and 45°30´-66°45´W in the central and northeastern Amazon region of Brazil, the Guianas, and Venezuela, at 195(7-725) m elevation in lowland rainforest (map).

There is clinal variation in this species. Linear regression shows there are significant (P <0.05) associations between elevation and four inflorescence variables. Squared multiple R for the regression of distance between bract scars on elevation is 0.54, peduncle length 0.18, peduncle width 0.11, and number of rachillae 0.12. These variables increase with increasing elevation.