Garden flowers: Insect visits and the floral reward of horticulturally-modified variants

Garden flowers can be valuable to wildlife if they produce nectar, pollen and/or seeds. To provide information needed by gardeners to select wildlife-friendly plants, we investigated nectar production and insect visits to Tropaeolum majus, Consolida sp., Antirrhinum majus, Viola x wittrockiana, Tagetes patula and Alcea rosea, in each case comparing a near-original flower type with a cultivar that had spurless, doubled, peloric or enlarged flowers. All species showed high secretion rates and standing crops of nectar. In most cases the horticultural modifications affected the numbers or species composition of the assemblage of insect visitors, and they generally reduced the value of the floral reward to insects, often affecting accessibility. Effects on seed yield were not investigated directly here, but are likely to further reduce the wildlife value of modified variants.