Serruria flagellifolia, the Houwhoek spiderhead, is a flowering shrub that belongs to the genus Serruria and forms part of the fynbos. The plant is endemic to the Western Cape and occurs in the Kogelberg, Greenlandberg and Babilonstoringberge. The shrub grows up to 1.0 m tall and flowers from June to November.
Fire destroys the plant but the seeds survive. Two months after flowering, the fruit falls and ants disperse the seeds. They store the seeds in their nests. The plant is unisexual. Pollination takes place through the action of insects. The plant grows in sandstone soil at elevations of 150 – 400 m.