With more than 400 species, Aloe is one of the largest groups of succulents. The most widely planted aloe, Aloe vera, is a favorite house plant and has naturalized in North Africa, India, the Caribbean, South America, and other frost-free areas, according to the Cactus and Succulent Society of America. Originating largely in Africa and the Arabian Peninsula, aloe is grown primarily for its spiky leaves, but many aloes also produce flowers.
The aloe vera plant is the most familar and widely cultivated aloe. Gel from inside aloe vera leaves is used as a first aid treatment for burns, herbal remedies, food supplements, and in cosmetics. Succulent grayish green leaves up to 20 inches long grow from a dense rosette at the plant's base. Aloe vera produces offset pups, which are propagated and grow to adult size in individual containers.
The largest African tree aloe is Aloe barberae, reaching almost 50 feet high with a stem diameter of approximately 3 feet. Unlike aloe vera, propagation is usually from seeds or stem cuttings. Another tree aloe is Aloe dichotoma (quiver tree). The quiver tree can grow to 30 feet. Native to South Africa and Namibia, tree roots are used in traditional medicine to treat asthma and tuberculosis.
Aloe marlothii is known as the mountain aloe. Described by Kew Gardens as "one of the most iconic of the hundreds of aloes occurring in Africa," this species fills South African hillsides with hundreds of plants. This is a tall aloe, 6 to 12 feet tall and rosette crown. Leaves are dull green with numerous short spikes on leaf edges and flat surfaces. Some ethnomedical uses of Aloe marlothii leaf gel include treating internal parasites in humans and livestock.
Miniature aloes include Aloe descoingsii, labeled the world's smallest aloe. A native of Madagascar, individual heads are approximately 1 1/2 inches across. Triangular leaves with whitish specks sit below small orange flowers. A little bigger is Aloe jucunda, with heads slightly larger than 2 inches. Another miniature aloe is Aloe haworthioides, with 2-inch heads, dark green leaves and hairy bristles.