Phylogeny of Fargesia (Poaceae: Bambusoideae) and infrageneric adaptive divergence inferred from three cpDNA and nrITS sequence data

Fargesia , a temperate woody bamboo genus, is one of the largest genera and constitutes a taxonomically problematic group due to unusual life cycles and the rarity of flowering. We explored phylogenetic relationships within Fargesia and its allies based on sequence data from three cpDNA regions ( mat K, psb A- trn H and trn L- trn F) and one nuclear region (nrITS). A representative sample of 49 species, including 36 Fargesia and nine Yushania , were sampled, and maximum parsimony, maximum likelihood and Bayesian inference were used to reconstruct the phylogeny of Fargesia . The results suggest that Fargesia is polyphyletic, with F. crassinoda and F. damuniu in the Thamnocalamus clade, F. ampullaris , F. semiorbiculata , F. gyirongensis and F. collaris in the Drepanostachyum + Himalayacalamus clade, and the rest of species of Fargesia and all sampled species of Yushania in a Fargesia + Yushania clade, which was further divided into weakly supported Fargesia spathe and non-spathe clades. Species in the Fargesia spathe clade have the derived “spathe-like leaf sheath syndrome,” which may have evolved as a result of an adaptive advantage of compressed inflorescences in colder temperatures.