狭叶花柱草（学名：Stylidium tenellum）为花柱草科花柱草属下的一个种。

Stylidium tenellum is a dicotyledonous plant that belongs to the genus Stylidium (family Stylidiaceae). It is an annual plant that grows from 5 to 27 cm tall. The obovate or elliptical leaves, about 6-14 per plant, are scattered along the elongate, glabrous stem and are generally 3.5-8.5 mm long and 0.8-2.5 mm wide. Scapes are absent. Inflorescences are 2-8 cm long and produce white, pink, or mauve flowers that bloom from September to December in their native range. S. tenellum is endemic to Southeast Asia and its distribution ranges from southern India to southern China and south to Sumatra. In China it's known from Guangdong, Yunnan, and southern Fujian provinces. Its habitat is recorded as being seasonal swamps and is often reported to grow near rice paddies. It is usually found growing at low altitudes but has been recorded from elevations as high as 1100 metres on Sumatra. S. tenellum is most closely related to S. diffusum.