Phyllostachys (/ˌfɪloʊˈstækᵻs, -lə-, -ˈsteɪ-/)is a genus of Asian bamboo in the grass family. Many of the species are found in Central China, with a few species in northern Indochina and in the Himalayas. Some of the species have become naturalized in parts of Europe, Asia, Australia, and the Americas. The stem or culm has a prominent groove, called a sulcus, that runs along the length of each segment (or internode). Because of this it is one of the most easily identifiable genera of bamboo. Most of the species spread aggressively by underground rhizomes.