Phylogenetic Relationships among Species in the GeneraChisochetonandGuareaThat Have Unique Indeterminate Leaves as Inferred from Sequences of Chloroplast DNA

Meristematic activity associated with the acropetal differentiation of the young primordia of leaflets is detectable at the tips of the primordia of some pinnately compound leaves. However, this activity vanishes upon differentiation of the terminal leaflet. The indeterminate compound leaves of members of the genus Chisocheton in Southeast Asia and of the genus Guarea in the New World and Africa (Meliaceae) are unique and can develop indeterminately as a result of the activity of the leaf apical meristem. We performed a molecular phylogenetic study of these genera and compared three regions of chloroplast DNA in an effort to identify the evolutionary origin of this type of indeterminate leaf in Meliaceae. Our results indicate that indeterminate leaves evolved only once during the course of differentiation of these genera, with subsequent divergence that led to two genera with indeterminate leaves, namely, Chisocheton and Guarea. Moreover, the results obtained from our molecular phylogenetic analysis, based on the trnL‐F and psbA‐trnH intergenic sequences and the sequence of the trnL intron, do not support most previously published subgeneric groupings in earlier taxonomic classifications of the genus Chisocheton.