Sinosasa (Poaceae: Bambusoideae), a new genus from China

Sasa is a taxonomically problematic genus of bamboos mainly distributed in Japan and China. Recent phylogenetic analyses demonstrated that Sasa is polyphyletic, with Chinese species of Sasa being distantly related to species from Japan. Based on newly collected flowering materials from China, it was found that the Chinese species hitherto placed in Sasa subg. Sasa have racemose synflorescences, 2-3 florets per spikelet with a rudimentary terminal floret, and 3 stamens and 2 stigmas per floret. This distinguishes them from the type of Sasa and other species of that genus, which have paniculate synflorescences, 4-10 florets per spikelet, and 6 stamens and 3 stigmas per floret. Together with several differences in vegetative characters between these two groups, this morphological distinction warrants recognition of a new genus for the Chinese species hitherto placed in Sasa subg. Sasa. The results of our molecular phylogenetic analyses also strongly support the monophyly of the Chinese representatives of Sasa subg. Sasa. The new genus Sinosasa is described to accommodate the Chinese species, including three previously recognized species and four new species.