A Rhodocoma arida plant bears stiffly erect culms to heights around 2 m. It is commonly known in Afrikaans as dekriet (thatching reed), which indicates the plant's general use. This name is shared with several other restios, some in the Chondropetalum, Elegia, Thamnochortus and more genera of the Restionaceae family.
R. arida forms clumps and does not resprout after fire. It does not grow sterile stem-branchlets, the unbranched culms often blue green or blue grey with persistent sheaths. The species is taller than several of the related restio type plants of the region.
The female inflorescences consist of many small, stiffly erect spikelets as in the photo. There are several bracts on a spikelet and six perianth segments in a floret. These segments are hard and nearly equal, the outer ones longer and narrower. The three styles are exserted from open florets.
The species distribution is in the southeast of the Western Cape, mostly on mountain slopes in and around the Little Karoo. The photo was taken on Minwater near Oudtshoorn.
The habitat is arid, rocky and sandy fynbos slopes. The species is not considered threatened in habitat early in the twenty first century (Vlok and Schutte-Vlok, 2015; Leistner, (Ed.), 2000; iNaturalist; http://redlist.sanbi.org).