TYPES OF NECTAR IN ANGIOSPERMS

S ummary1 The nectar of 889 species and some fifty varieties of Angiosperms has been analysed by paper partition chromatography. 2 Ten different types of nectar are distinguished (with two or three very uncommon types in addition) and are broadly classified into:(a)  Nectars with dominant sucrose. (b)  Balanced nectars with about equal amounts of sucrose, fructose and glucose. (c)  Nectars with dominant fructose + glucose.3 Three oligosaccharides occurring in nectar are identified and a fourth is named tentatively. 4 Eight hundred and twenty‐eight species appear to have nectar of constant composition: sixty‐one species have nectar which varies distinctly. The variation does not appear to be linked with locality or date of sampling. 5 The distribution of nectar types is traced through the Herbaceae. 6 Sucrose‐dominated nectars appear to be associated with long‐tubed flowers having protected nectar, and fructose +glucose‐dominated nectars with ‘open’flowers having unprotected nectars. 7 Many humble‐ and honey‐bee, butterfly and moth flowers have nectars with sucrose more or less strongly predominating over fructose and glucose. 8 The climax groups of the Cruciferae, Umbelliferae, a section of the Compositae, the Euphorbiales and the herbaceous Rosaceae have a completely broken‐down nectar of equal parts of fructose and glucose which is technically honey. 9 The preference of Apis mellifera for certain sugar mixtures and the types of nectar in some honey‐bee flowers are explored.