Monographs Details: Acanthella plicata Gleason
Authority: Maguire, Bassett, et al. 1953. The Botany of the Guayana Highland. Mem. New York Bot. Gard. 8 (2): 87-160.
Description:Latin Diagnosis - Frutex parce ramosus, internodiis glabris, nunc elongatis, nunc brevissimis; folia arete conduplicata, coriacea, late obovata; seminum ala coriacea opaca.
Species Description - Widely branched shrub up to 3 m. tall; internodes of the long shoots 5-8 cm. long, obscurely angled; internodes of the short shoots 2 or 3, each about 1.5 mm. long; nodal setae none Petioles stout, 4-10 mm. long; blades coriaceous, permanently closely folded, obovate-oblong, up to 6 cm. long and 4 cm. wide, broadly rounded to a minutely refuse tip with a blunt tooth in the sinus, entire, rounded at base, glabrous, 3-nerved, the lateral pair submarginal and very obscure. Flowers solitary, on a peduncle 10-12 mm. and a pedicel 6-8 mm. long. Seeds concavely flattened, about 5 mm. long and 4 mm. wide, the wing firm, opaque, nearly 1 mm. wide.
TYPE: on granite rocks at low altitudes, Rio Cuao between Cerro Sipapo and the Orinoco River, Amazonas, Venezuela, Bassett Maguire & Louis Politi 29027; New York Botanical Garden. Even when fresh, the leaves cannot be unfolded without tearing.
The four known species may be distinguished by the following key:
Stem bearing stiff setae at each leaf-bearing node; leaves acute, tipped with a short stiff spine; hypanthium glandular-hirsute.
Seeds with firm opaque wing; long and short shoots well differentiated; leaf-blades 1—3 cm. long; plants growing on granite at low altitudes.
A. conferta.Seeds with very thin hyaline wing; all internodes very short; leaf-blades up to 13 mm. long; plants growing on sandstone at high altitudes.
Stem without nodal setae; both long and short shoots developed; leaves broadly rounded at the summit, not setose-tipped; hypanthium apparently glabrous; plants growing on granite.
Leaves flat, spatulate to obovate-oblong; seeds 5-7 mm. long.
Leaves permanently folded, very broadly obovate-oblong; seeds 4-5 mm. long.