The genus Greyia has been placed ing the Greyiaceae family. The other two species in the Greyiaceae family, Greyia radlkoferi and G. sutherlandii are dormant and leafless in winter, unlike G. flanaganii, which is evergreen. G. radlkoferi is found in Mpumalanga and Limpopo (Northern Province) and G. sutherlandii is from KwaZulu-Natal. The greyias of South Africa do not appear to have close relatives among the extant flora of the world. Greyiaceae belongs in the monotypic order Greyiales that was formerly described and placed between the Saxifragales and Francoyales.

This is a stunning shrub or small, much-branched, evergreen tree that grows up to 3 m in height. The bark is smooth and pale brown. Greyia flanaganii commonly known as Kei Bottlebrush in English and Kei Baakhout in Afrikaans has showy, bright red, bell-shaped flowers during spring (from August to October). The nectar-rich flowers attract many insects such as honeybees, as well as pollinators like sunbirds. Greyia flanaganii is a rare endemic of Eastern Cape, where it is found on the grassy hillsides and among rocks on the steep slopes of the Kei River and its tributaries, the Toise and Kabusi Rivers. The seedlings are tiny and fragile. This may be the reason why these shrubs are often found emerging from fissures in rocks. The Xhosa people place the roots of this Eastern Cape tree on either side of their kraals (enclosures) as it is thought to ward off sickness and prevent theft of livestock.