Straight From the Plastome: Molecular Phylogeny and Morphological Evolution of (Bambusoideae: Poaceae).

is ecologically and economically important in mountainous forests. Many species are also important sources of food for some endangered animals such as the giant panda. Recent molecular phylogenetic analyses have revealed as a polyphyletic group despite some unclear lineage affinities. In the present study, we reconstructed the phylogeny of and its allies, including (incl. ), and , from a plastome sequence matrix that contained 20 and five species as ingroups, 16 species from nine other bamboo genera plus and as outgroups. and its allies were broken into eight clades. Several species were clustered into the clade and the + clade that rendered the polyphyly of . The remaining six clades, including the spathe clade, the clade, , the clade, the clade, and the clade, were identified. Molecular phylogenetic analyses supported that should be included in (s.l.) which had synapomorphy of expanded leaf sheaths in varying degree at the basis of inflorescences, and further divided into the spathe clade, the clade, and the clade. All sampled species of were nested within the clade. The probable model of the origin of the species in the spathe clade with spathe-like leaf sheath syndrome was proposed. Moreover, the formation of the spathe-like leaf sheath syndrome may be correlated with cold climatic conditions in Quaternary. Our results provide new sight into the phylogenetic relationship within .