Monographs Details: Chorisepalum ovatum Gleason
Authority: Maguire, Bassett. 1978. The botany of the Guayana Highland--part XI. Mem. New York Bot. Gard. 32: 1-391.
Discussion:The type, a unicate collection and rather poor specimen, at the time of the original study had the single flower removed, but sketches made on the type sheet by Gleason illustrate critical floral characters. In the original description Gleason and Wodehouse (1931) wrote "Flores solitarii terminates 6-meri." The flower arrangement, however, is to be expressed as 4-6-6-2 for Chorisepalum ovatum and for the other species of the genus. Dissections of flowers from three collections made on Cerro Sipapo seem to confirm the consistency of this 4-6-6-2 flower arrangement.
The form of the calyx is unique. The outer two sepals are laterally dorsally 2-wing-keeled. The two inner sepals are wingless but provided with a low median dorsal keel. These observations require the generic description to be so emended.
Two forms of Chorisepalum ovatum at least occur on Cerro Sipapo, differing in habit and facies. The var ovatum characteristically is a taller shrub with larger, thicker, less acute leaves. The var sipapoanum is less high, with smaller usually acuminate leaves. Intermediates occur.