Origins of woodiness in Balsaminaceae

The family Balsaminaceae, which contains the species-rich genus Impatiens and the single-species genus Hydrocera (H. triflora), is essentially herbaceous and is nested into a largely woody clade of Ericales. Lens et al. compare a molecular phylogeny of Balsaminaceae with wood anatomical observations to determine whether the woodier species are derived from herbaceous relatives (i.e. secondary woodiness), or whether (primary) woodiness represents the ancestral state. The data show that secondary woodiness has evolved at least five times in parallel within Impatiens; however, these parallel shifts are indistinct because of the continuous variation in wood development between herbaceous and woody species.