Background:

Gymnopodium floribundum is a dominant tree in the seasonally tropical dry forests of Yucatan, Mexico. This species shows a large floral display size during short periods, but a very low seed-set has been reported.

Questions:

What type of dichogamy does G. floribundum exhibit? What is its compatibility system?

Study species:

G. floribundum, a dichogamous tree of importance in beekeeping.

Study sites and dates:

Xtmakuil, Yucatan. February-March and November-December 2022.

Methods:

Floral sexual function synchrony and sexual expression was recorded during the flowering season. The compatibility system was evaluated with a hand-pollination experiment.

Results:

Intra-floral overlap of sexual functions was low (< 2 %), but relatively high between flowers of different inflorescences (0.48 ± 0.13, Mean ± SD) and between flowers of different trees (0.64 ± 0.11, Mean ± SD). Mature fruit production by hand self-pollination was low (ca. 3 %) and 6 times lower with respect to cross.

Conclusions:

G. floribundum shows complete intrafloral dichogamy, but incomplete intra- and interindividual dichogamy. Sexual expression changed throughout flowering, from predominant male bias to female. Although G. floribundum is self-compatible, the results suggest a wide advantage of cross-pollination over self-pollination.