Named after Rudolf Marloth, a South African botanist,  this unbranched large aloe  often grows up to 10 feet tall and normally has a trunk densely covered by the withered old leaves.  Mountain Aloe leaves can be up to 4′ feet in length, gray-green color, with reddish-brown spines along the margins and randomly on other parts of the leaf.

In late fall to late winter appears the wide-spread branching inflorescence bearing yellow to red-orange flowers.   Plant in full sun in a well-drained soil.   Requires little to no supplemental irrigation in coastal California gardens.  this species of aloe has an especially large robust head of stiff, grey-green leaves.

Flowering takes place through the winter months.

The distinctively horizontal branches of its inflorescence is an easy way to distinguish this species from other aloes. For this reason it is sometimes known as the Flat-Flowered Aloe.