Morphology and Anatomy of Fruits in New World Boehmeria in Relation to Taxonomy

Abstract

The fruits of 9 of the 13 indigenous species of Boehmeria in the New World were examined. Fruits were found to be either 'achene-like' with thin dry exocarp, or 'drupe-like' with slightly fleshy, mostly mucilaginous, exocarp. Achene-like fruits, found so far only in the New World representatives of the genus, exhibit putatively primitive pericarp structure; drupe-like fruits appear to be a derived condition. The tubular fruiting perianth consists of much-compressed cells and is usually difficult or impossible to detach from the pericarp, especially in drupe-like fruits. Considerable diversity of pericarp structure is found: exocarp with or without mucilage and tannins; mesocarp of 1 6 layers of cells, partly or entirely crystalliferous; ribs, formed by the pericarp on the narrow sides of the fruit and consisting usually of sclerenchymatous or lignified parenchymatous tissues, are developed to different degrees between species or within one species, and are sometimes expanded into wings. Fruit structures were classified into two main groups; these and their subgroups correlate with, and add to, the earlier classification based on gross morphology; certain evolutionary trends are suggested and compared with previous findings.