An updated description of Parkia barnebyana (Leguminosae: Caesalpinioideae, mimosoid clade) from Amazonian Venezuela and Brazil, and comparison with other species in sect. Parkia with erect capitula

Abstract

SummaryAn updated description, including characters of the capitulum and fertile flowers, is provided for Parkia barnebyana. Originally recorded from southern Venezuela, this small canopy tree from igapó (blackwater flooded forest) is now also known by two collections from north-western Brazil. The capitula are yellow and held erect, with the fertile flowers uppermost; they are borne on short, robust, upright peduncles that arise from long compound inflorescence axes projecting directly above the crown. The structure and shape of the capitula place this species in pantropical sect. Parkia and its pod morphology suggests that it lies outside the largely Amazonian nitida-group; both conclusions are supported by a recent phylogenetic analysis. The indehiscent pods remain in the tree at maturity and most seeds are apparently removed by arboreal dispersers and vertebrate seed predators. Two other neotropical species in sect. Parkia, P. cachimboensis and P. decussata, are known to have erect, yellow or largely yellow capitula and in both, a well-developed fringe of staminodia projecting from the basal flowers is absent. Both these species are chiropterophilous and although we predict that P. barnebyana is also likely to be bat-pollinated, we have made no observations. A fourth neotropical species, P. nana, also with yellow flowers, is reported to have erect capitula but they do have staminodial fringes; its pollination has not been studied. Within sect. Parkia, erect capitula occur only in the Neotropics, probably because of the head-down position in which quite large generalist phyllostomid bats land on them to access nectar. Erect capitula appear to have evolved more than once within neotropical sect. Parkia and at least sometimes from ancestors with pendent capitula, but further phylogenetic data are needed to confirm this.