Monographs Details: Cephalocarpus rigidus Gilly
Authority: Maguire, Bassett. 1965. The Botany of the Guayana Highland. Mem. New York Bot. Gard. 12 (3): 1-285.
Description:Distribution and Ecology - Distribution. Cephalocarpus rigidus in this revised sense has a range extending throughout all of Venezuelan Guayana on Roraima sandstone. Similar distribution patterns are presented b,v Didymiandrum stcUatum, Everardia montana and Exochogyne amazonica, which seem to have expanded well over the potential area determined by edaphic factors. VENEZUELA. Amazonas: Cerro Sipapo, Maguire d Politi 27592 & 27826. Cerro Yutaje, Maguire d Maguire 35389; Serrania Paru, Cowan d Wurdack 31337; Cerro Huachamacari, Maguire, Cowan d Wurdack 30070 d 30159; Cerro Duida, Maguire cO Maguire, Jr. 29212, Tate 720, 721 (NY, holotype of C. rigidus var. mucronatus, from summit, 6800 ft. Ridge 16), Tate 1035 (NY, holotype of G. lineariifolius, from fiat near stream at Central Camp at summit, 4800 ft) Tate 1345 (NY, holotype of C. longihracteatus). Bolivar: Cerro Guaiquinima Maguire 32764, 32831, 32911, 33054; Anyan-tepui, Vareschi d Foldats 4877; Chimanta Massif, Steyermark c& Wurdack 805, 1120; Ptari-tepui, Maguire & Wurdack 33916, Steyermark 59640 (F, holotype of C. steyermarkii; N Y , isotype from scrubby forest on rocky open portion of plateau on southeast slopes, alt 1600 m ) ; Ilu-tepui, Maguire 33393, 33632; Uei-tepui (Cerro do Sol), Steyermark & Nilsson 342, 609. BRITISH GUIANA . Pakaraima Mts., Maguire d Fanshawe 32051; Kaieteur Plateau, Maguire d Fanshawe 23453 (NY, holotype of C. maguirei, from Kaieteur savannas).
Discussion:Cephalocarpus rigidvs var. typicus Gilly, Bull. Torrey Club 69: 296. f. 1 g-i. 1942.
Cephalocarpus rigidus var. mucronatus Gilly, Bull. Torrey Club 69: 296. f. 1 j-l. 1942. Syn. nov.
Cephalocarpus longibracteatus Gilly ex Gleason & Killip, Brittonia 3: 153. f. S d-j. 1939. Syn. nov.
Cephalocarpus lineariifoliits Gilly, Bull. Torrey Club 69: 295. f. 1 f. 1942. Syn. nov.
Cephalocarpus maguirei Gilly, Bull. Torrey Club 76: 292. 1949. Syn. nov.
Cephalocarpus steyermarTcii Gilly, Fieldiana Bot. 28(1): 54. 1951. Syn. nov.
Variations in Cephalocarpus rigidus, the only widespread species of the genus, have been observed from the ample collections kept at The New York Botanical Garden. Inflorescences vary most markedly from a fascicle of several clusters of spikelets as much as 3 cm long to almost a single head with several spikelets about 1 cm in diameter. The bracts and floral glumes vary in length in accordance with the size of inflorescence. The range of the length of fructifications is from 1.5 to 2.2 mm . Leaf blades vary in the density of pubescence. N o discontinuity was found in any of these characters. All species and varieties described by Gilly under his subgenus Neocephalocarpus fall within the variation range mentioned above, and hardly represent discrete taxa even at infraspecific levels. All of these names are, therefore, united under the earliest valid name, Cephalocarpus rigidus
Distribution:Guyana South America
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