Chemicals from Aloe species derive in the main, from two separate parts of the leaves of these well known succulent plants. The root chemistry is less well known. Aloe gel is the contents of the leaf parenchyma and properly prepared, is colourless and tasteless, containing substances useful especially for healing skin complaints. Water soluble substances isolated from this material include polysaccharides and lectins, some of which show biological activity. Aloe leaf exudate is usually brown and bitter and originates from specialized cells adjacent to the leaf vascular bundles. It contains anthraquinone and chromone derivatives and other phenolics. The range of compounds is characteristic of a particular species but not unique to it.