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This brief review describes and discusses some chemical substances that have been found in a synoptic survey of flowering plant nectars. The ever-present sugars are not considered. Amino acids are universally present, in amounts up to about 4 mg /ml 1. Nectars are richer in amino acids if the flowers that produce them are pollinated by settling moths, butterflies and many wasps which, as adults, do not have alternative sources of protein-building materials. They are weaker in the cases of flowers pollinated by bees and bats (which utilize pollen as a nitrogen source) and birds that catch insects. In addition to potentiality for increasing life span and reproductive output of pollinating insects, amino acids in nectars of all kinds may help to privide a distinctive « taste » to the nectar of each species. Nectar amino acid complements appear to be strictly controlled genetically; these complements have a use in taxonomic and phylogenetic studies of congeneric species. Extra-floral nectar produced on the