TYPES OF NECTAR IN ANGIOSPERMS

Abstract

Summary: The nectar of 889 species and some fifty varieties of Angiosperms has been analysed by paper partition chromatography. Ten different types of nectar are distinguished (with two or three very uncommon types in addition) and are broadly classified into: Nectars with dominant sucrose. Balanced nectars with about equal amounts of sucrose, fructose and glucose. Nectars with dominant fructose + glucose. Three oligosaccharides occurring in nectar are identified and a fourth is named tentatively. 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. The distribution of nectar types is traced through the Herbaceae. 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. Many humble‐ and honey‐bee, butterfly and moth flowers have nectars with sucrose more or less strongly predominating over fructose and glucose. 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. The preference of Apis mellifera for certain sugar mixtures and the types of nectar in some honey‐bee flowers are explored.