Aloes occupy a wide range of habitats, varying from forests to exposed rock surfaces and cliff faces. The genus does not occur in moist lowland forest, but the dry coastal forests of eastern Africa include arborescent species such as A. eminens and A. volkensii Engl. subsp. volkensii. Not all arborescent species are forest trees, the huge A. dichotoma L. being a prominent feature of the arid Namaqualand landscape. Many shrubby species are found in Acacia scrub and other thickets, sometimes depending on the surrounding vegetation for support (e.g. A. morijensis S.Carter and Brandham). Grasslands offer another habitat, especially for many acaulescent species, such as A. lateritia Engl. and A. secundi-flora Engl. Several species, including A. chrysostachys Lavranos and L.E.Newton and A. classenii Reynolds, occur on expanses of rocks, rooted into soil pockets or crevices. Most of the species formerly included in the genus Lomatophyllum occur in moist coastal forests of Madagascar and several Indian Ocean islands.
The genus occupies a considerable altitudinal range. Aloes may be found from sea level (e.g. A. boscawenii Christian, A. kilifiensis Christian) up to about 3,500 meters above sea level (e.g. A. ankoberensis M.G.Gilbert and Sebsebe, A. steudneri Schweinf. ex Penz.). On the east side of the continent tropical conditions occur at sea level, whilst at the higher altitudes the plants are subjected to cold conditions and may even be covered by snow for a while, especially in southern latitudes (e.g. A. polyphylla Schonl. ex Pillans). In South Africa Aloe haemanthifolia Marloth and A.Berg. grows on cliffs near waterfalls and for at least part of the year has water running down through the clumps of rosettes.
In the wild, aloes occur on a wide range of soil types and substrates. Some seem to be restricted to certain substrates, including dolomite (e.g. A. alooides (Bolus) van Druten), granite (e.g. A. torrei Verd. and Christian), gypsum (e.g. A. breviscapa Reynolds and Bally) and limestone (e.g. A. calcairophila Reynolds). However, the success of most species in cultivation suggests that they are tolerant of the many soil types to be found in gardens and potting mixtures.
Some Aloe species are found as dense populations (e.g. A. falcata Baker), whilst others occur as scattered individuals (e.g. A. variegata L.). They are often prominent, but rarely dominant in the ecological sense, except where the vegetation is sparse and they are the only large plants around (e.g. A. pillansii Guthrie).
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