Aloe castanea received the specific epithet of castanea for the eponymous colour designation, chestnut. The red-brown perianths have inner segments broader than the outer three free ones. The inner three anthers as well as the outer ones are in turn excerted.

Copious quantities of dark nectar, sticky and sweet, are produced. This is much valued by birds, as well as bees and other insect pollinators. The up to 1 m long, unbranched raceme with its characteristic graceful curve and upturned apex earned the plant the name of cat’s tail aloe. The inflorescence in picture has not this year reached its best size (Reynolds, 1974; Jeppe, 1969).