Aloes are indigenous to East and South Africa, but have been introduced into the West Indies (where they are extensively cultivated) and into tropical countries, and will even flourish in the countries bordering on the Mediterranean.
They are succulent plants belonging to the Lily family, with perennial, strong and fibrous roots and numerous, persistent, fleshy leaves, proceeding from the upper part of the root, narrow, tapering, thick and fleshy, usually beset at the edges with spiney teeth. Many of the species are woody and branching. In the remote districts of S.W. Africa and in Natal, Aloes have been discovered 30 to 60 feet in height, with stems as much as 10 feet in circumference.
The flowers are produced in erect, terminal spikes. There is no calyx, the corolla is tubular, divided into six narrow segments at the mouth and of a red, yellow or purplish colour. The capsules contain numerous angular seeds.
The true Aloe is in flower during the greater part of the year and is not to be confounded with another plant, the Agave or American Aloe (Agave Americana), which is remarkable for the long interval between its periods of flowering. This is a succulent plant, without stem, the leaves being radical, spiney, and toothed. There is a variety with variegated foliage. The flower-stalk rises to many feet in height, bearing a number of large and handsome flowers. In cold climates there is usually a very long interval between the times of its flowering, though it is a popular error to suppose that it happens only once in a hundred years for when it obtains sufficient heat and receives a culture similar to that of the pineapple, it is found to flower much more frequently. Various species of Agave, all of which closely resemble each other, have been largely grown as ornamental plants since the first half of the sixteenth century in the south of Europe, and are completely acclimatized in Spain, Portugal and Southern Italy, but though often popularly called Aloes all of them are plants of the New World whereas the true Aloes are natives of the Old World. From a chemical point of view there is also no analogy at all between Aloes and Agaves.