Similarity and Apparent Convergence in the Nectar-Sugar Composition of Some Hummingbird-Pollinated Flowers

The nectar-sugar composition of 40 species of purportedly hummingbird- pollinated plants in 12 families was determined by high-performance liquid chromatography. The distribution of relative percentages by mass for the major sugars--fructose, glucose, and sucrose--was normal about their means. The means and 95% confidence limits were: fructose, 15% (3%-33%); glucose, 11% (0%-23%); and sucrose, 74% (55%-94%). One sample also contained a trace of maltose. Salvia spathacea contained only fructose and sucrose. The data, primarily from southwestern North America, define a range of nectar composition, possibly representing the preferences of hummingbirds. These data support assertions of adaptive convergence in the sugar composition of nectar in hummingbird-pollinated species.