Annals of Botany

New insights into the evolution of the florally diverse Detarioid legumes

The Brazilian tree Goniorrhachis marginata is the only species of its genus in the bean family (Leguminosae) with striking flowers consisting of a long floral tube and regular corolla redolent of the rose family. Prenner and Cardoso study floral development with a scanning electron microscope and analyse the results in a broad phylogenetic context.

Goniorrhachis marginata
Goniorrhachis marginata

Key observations were that the 4-merous calyx has resulted from complete loss of one sepal and that formation of the regular corolla originates from a typical caesalpinioid pattern with the upper petal innermost (ascending aestivation) and the young style bending away from the inflorescence axis. The authors propose a new synapomorphy for the clade further to an extensive dataset analysis showing that abaxial bending styles characterise all major lineages of Detarioid legumes

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