Systematic relevance of seedling morphology in Acosmium, Guianodendron, and Leptolobium (Leguminosae, Papilionoideae)

Abstract

Morphological and taxonomic studies have proposed changing the circumscription of Acosmium, with the recognition of two additional genera, Leptolobium and Guianodendron. A study on seedling morphology of all accepted species of Acosmium s.str., five species of Leptolobium, and Guianodendron praeclarum is presented, aiming to evaluate the systematic value of these characters. Guianodendron has crypto-hypogeal reserve seedlings, while Acosmium and Leptolobium have phanero-epigeal seedlings with foliaceous cotyledons. The latter two genera are distinguishable from each other mainly by hypocotyl shape, ratio of hypocotyl length to epicotyl length, nyctinasty of leaflets and cotyledons, shape and venation of cotyledons, stipule and leaflet morphology, presence or absence of intercotyledonary glands, and presence of glands on other vegetative parts. In conclusion, seedling morphology data provide relevant systematic characters that support the proposed changes in the generic delimitation of Acosmium.