Breeding System of Jacquemontia curtisii, an Endemic Morning-Glory of Pine Rocklands

The pine rocklands of southern Florida are a globally imperiled ecosystem, and as a result many species endemic to this habitat are endangered or threatened. To help conserve the endemic plants of the imperiled pine rockland habitat in southern Florida, it is important to understand factors that influence their successful reproduction. Field-collected individuals of Jacquemontia curtisii Peter ex Hallier f. (Convolvulaceae), a threatened species of perennial herb, were grown in a greenhouse to control conditions for floral measurements and hand-pollinations. While flowering lasts for months, individual flowers last one day, open from dawn through mid-morning, and produce nectar as reward for pollinators. Each flower contains 0.25–1 μL of nectar, with 22–50% sugar on a wt/wt basis; larger nectar volumes usually corresponded to lower sugar concentrations. Plants with larger flowers have smaller nectar volumes than those with smaller flowers, but higher nectar sugar concentrations. Flowers were subjected to one of four pollination treatments: not manipulated (autonomous selfing), anthers removed (emasculation), selfed, or crossed. Five or ten flowers on each plant received each treatment, except for crosses, where ten to twenty flowers were used, crossed with pollen from different individuals. The results show the species to be highly self-incompatible, but some individuals (one-fifth of the plants studied) are able to set fruit also with their own pollen. Fruit set observed in the field can be interpreted as evidence of pollinator activity with successful transfer of pollen from mostly other compatible individuals. There is therefore a danger of species decline if small habitat fragments contain only individuals that are closely related.