Cotyledon anatomy in the Leguminosae

Cotyledon anatomy has been investigated in approximately 900 species representing all the major tribes of the Leguminosae. Four main cotyledon forms are recognized on the basis of morphological, anatomical and functional criteria. The two modal forms are a leaf-like photosynthetic cotyledon, usually borne in an endospermic seed and occurring in about 60% of species; and a fleshy, storage cotyledon, borne in a non-endospermic seed and occurring in about 30% of species. Two intermediate forms combine the structural and functional characteristics of the modal forms in varying degree. The leaf-like cotyledon is considered to be the basic form from which the others have been derived. Cotyledon anatomy shows correlations with seed size and with taxonomic grouping at the tribal and generic levels and thus provides a set of minor characters of potential taxonomic or phylogenetic value or for use in seed and seedling classification and identification.