Chasmogamous and Cleistogamous Pollination in Salpiglossis sinuata

Pollen from chasmogamous flowers of Salpiglossis sinuata L. could not be induced to germinate in vitro unless stigmatal extract was applied to the culture medium. The substance that induces pollen germination in the stigmatal extract is water‐soluble and heat‐stable. Crosses could not be achieved between chasmogamous and cleistogamous flowers because of structural incompatibility. Pollinated pistils of chasmogamous flowers release a large amount of ethylene. The burst of ethylene release is due to an interaction between pollen tubes and stylar tissue and is directly proportional to the quantity of pollen placed on the stigma. Cleistogamous flower buds also produce a burst of ethylene at the time of pollination within the closed flower. The ethylene release may be a cause of reduced corolla development associated with cleistogamous flowers.