Serruria gremialis, the Riviersonderend 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 Riviersonderend and Stettynkloof mountains. The shrub is predominantly a creeper with stems growing up to 1.0 m in length and flowering from July to February.
The plant's roots sprout again after a fire. 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 on the northern slopes in sandstone soil at elevations of 270 – 760 m.