Monographs Details: Lagenocarpus Nees
Authority: Maguire, Bassett. 1965. The Botany of the Guayana Highland. Mem. New York Bot. Gard. 12 (3): 1-285.
Description:Species Description - Plants monoecious or dioecious, perennial with short rhizomes sometimes with elongated stolons. Culms central, erect, triquetrous, several-noded, phyllopodic or aphyllopodic. Leaves with a linear blade, those of aphyllopodic species reduced to bladeless cataphylls toward the base of culms; sheaths long; contra-ligules produced, rounded-deltoid. Inflorescence consisting of several to many partial inflorescences, interrupted or more or less contiguous; partial inflorescences compound-paniculate, fascicled or more or less umbelliform, in monoecious plants the lower ones staminate and the apical ones pistillate. Staminate spikelets oblong-ellipsoid, many-flowered, single or clustered, sometimes congested in dense glomerules. Stamens 1 or 2 (sometimes up to 6) to a flower. Pistillate spikelets 1-flowered, single rarely paired at apex of peduncle; glumes imbricate, 5-7 or 3 to a spikelet. Fructifications trigonous, sometimes beaked, sometimes stipitate, smooth or foveolate rarely hispidulous, the utricle completely adnate to the achene; stigmas 3 (rarely 4 or more) ; hypogynous squamellae as a rule 3, minute, ciliolate, rarely needle-like.
Discussion:This genus is characteristically heterogeneous. H. Pfeiffer (1922) divided the genus into four sections chiefly based on the number of staminate flowers in a staminate spikelet and the manner of branching in partial inflorescences. We cannot agree with his classification. To our knowledge, the number of staminate flowers in a spikelet varies to some extent within a single species but does not vary appreciably between different species. The manner of branching shows a tendency to vary from paniculate to fasciculate branching, but this is insufficient for separating sections. Critical points for separation are in the structure of fructifications, the number of glumes in a pistillate spikelet, the type of pubescence of basal sheaths, and the feature of leaves especially whether they are radical or cauline. Species with stipitate fructifications always have pistillate spikelets with three glumes, whereas those with sessile fructifications always have pistillate spikelets with more than five glumes. The former are assigned to Acrocarpus, and can be further divided into two small groups by leaf arrangement. The latter also consist of two groups, which are characterized by different features of fructifications and inflorescences. The four sections that are thus regarded to represent natural groupings, m a y be classified as designated in the following key. Pfeiffer's names, retained for these sections, are largely accordingly amended.