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Heterochronic shifts of flower whorls initiation during evolution of Dipsacoideae. The flower diagrams are based on ontogenetic characters and the timing diagrams of flower whorls initiation are shown on the phylogenetic tree (based on Carlson et al., 2009). Note the correlation between reduction of sepal lobes in Dipknautids and delay in sepal initiation, and between multiplication of sepal lobes and extended period of initiation in Lomelosia and Pterocephalus.
