Bambusa lako, known in horticulture as Timor black bamboo, described without flowering material initially, is a common ornamental bamboo in Southeast Asia because of its moderate size and purplish-black culms when matured. During specimen examination at the Herbarium of the Singapore Botanic Gardens, a flowering collection of B. lako came to our attention. After careful dissection and comparison, we found that the reproductive characters resembled the genus Gigantochloa rather than Bambusa, such as short rachilla segments that do not disarticulate, terminal vestigial florets and filament tubes. Therefore, the floral features were supplemented and a new combination Gigantochloa lako was proposed.