Hawkmoth pollination of aerangoid orchids in Kenya, with special reference to nectar sugar concentration gradients in the floral spurs

• DOI: 10.3732/ajb.94.4.650
• Publication Date: 2008-02-29T22:42:44Z
• Authors: Dino J. Martins; Steven D. Johnson
• Keywords: Anthesis; Orchidaceae; Spur

The African orchid flora has a high proportion of species with long-spurred white flowers. Few data exist to test the prediction that this floral syndrome pattern reflects an important role for hawkmoth pollination in evolution and ecology these orchids. biology five aerangoid (Rangaeris amaniensis, Aerangis brachycarpa, A. confusa, thomsonii, kotschyana) was investigated Kenya. Four have long spurs (>10 cm) were pollinated by Agrius convolvuli Coelonia fulvinotata. which relatively short (ca. 4 cm), short-tongued hawkmoths Hippotion celerio Daphnis nerii. Nectar frequently filled entire spur some study species, even at anthesis. Sugar concentration nectar four found vary from ca. 1% mouth 20% tip. Gradients expressed more strongly long, straight spurs. Species spirally twisted showed both steep shallow gradients. These gradients, previously unknown plants, may function as "sugar trail," enticing long-tongued probe deeply into without incurring cost filling concentrated nectar. In addition, most is kept out reach pollinators.