Flora Zambesiaca
Taxon Detail
FZ volume:12 part:3 (2001) Aloaceae by S. Kativu
Aloaceae Key
Range:
A family of 7 genera from southern Africa and Madagascar, except for Aloe which extends northwards throughout tropical Africa and into the Arabian Peninsula.
Description:
Herbs, shrubs, or trees, often with thickened roots.Leaves usually perennial, fleshy, sheathing at the base and occasionally forming an underground bulb, in rosettes or spirally arranged, sometimes distichous, linear to lanceolate or ovate to triangular-conical; the margins with spine-tipped teeth or entire and sometimes ciliate; lamina smooth, rough or warty.Inflorescences pedunculate with flowers in 1–several terminal and axillary racemes, simple or paniculately arranged; bracts scarious, often sterile below the racemes, sometimes leaf-like on the lower part of the peduncle.Flowers bisexual, 3-merous, often zygomorphic, pedicellate, red, orange, yellow, white, or green, often bird-pollinated; perianth-segments 6, fused in the lower part to form a tube, the lobes in 2 whorls; stamens 6, inserted at the base of the ovary; ovary superior, 3-locular; style simple.Capsule dehiscing loculicidally.Seeds several to numerous in each locule, often winged.
Notes:
Genera are distinguished from other segregates of the Liliaceae sensu lato by their succulent leaves, vascular bundles in a ring around ground parenchyma, a cap of aloine cells at the phloem pole, chemical properties of the often coloured and/or pungent sap, and homogeneity of the chromosome composition.They have consistently been separated, by all workers, as a distinct group, tribe, subfamily or family.In recent treatments Dahlgren, Clifford & Yeo (Families of Monocotyledons: 181 (1985)) and Smith & van Wyk (Kubitzski, Fam. Gen. Vasc. Pl. 3: 130 (1998)) maintain these differences to distinguish the genera as the subfamily Alooideae within the Asphodelaceae.However, here the family Aloaceae is upheld as such differences, especially the conspicuously succulent leaves and constant chromosome number (2n = 14), together with tubular flowers and other more minor features such as spotting on the leaves, are considered to be diagnostic characters that separate the genera as a distinct and easily recognised family.Most genera are of horticultural value as garden ornamentals and are also collected by succulent-plant enthusiasts.This has led to the over-collection of some species, particularly for the hobbyist trade, and all Aloe species, and some species of related genera, are protected by CITES regulations.Many Aloe species also produce chemicals with recognised medicinal properties, especially as healing agents, and a few species are cultivated commercially for this purpose.Most species of each genus hybridise easily and advantage has been taken of this in horticulture.Many intergeneric hybrids have also been produced artificially, especially between Gasteria and Aloe, and between Gasteria and Haworthia.
