AbstractThe typical plant sterols contain a substituent at C‐24 of the side chain. This can be a methylene, ethylidene, methyl, or ethyl group; with the last three groups, all possible isomers have been reported in nature. The C‐24 alkyl groups are derived by a transmethylation reaction from methionine. The details of several distinct alkylation mechanisms, which are now recognized in a range of lower and higher plants, have been reviewed. The operation of these different routes may have some phylogenetic significance.