The central theme of the proposed research is to determine the role of dichogamy (temporal separation between male and female flowers), and herkogamy (spatial separation between male and female flowers) in promoting matings among individuals and/or preventing interference between male and female function both within and between flowers on individual plants. Dichogamy and herkogamy are widespread among angiosperms and are often found together; however, little is known about the precise role each contributes to an individual's reproductive success. The proposed study organism, hermaphroditic Sabatia angularis (Gentianaceae), is self- compatible, dichogamous and herkogamous. The role of dichogamy and herkogamy in influencing an individuals fitness will be quantified using chimeric plants when dichomgamy and herkogamy are (1) both functioning, (2) only one is functioning, and (3) neither is functioning . The role of dichogamy and herkogamy will also be examined as a function of flower age, size of floral display (in promoting self-pollinations between flowers on the same plant), and plant density. Pollen donors will be exactly determined using experimental plant arrays of unique genotypes known from allozyme markers. Male function will be determined by measuring pollen production, pollen removal rates and siring ability via allozyme markers in the same experimental plant arrays. Female function will be estimated by quantifying pollen deposition onto stigmas and seed set per fruit. These studies explore basic aspects of plant pollination and reproduction.