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Reproductive Biology of Three Wildflower Species: Implications of Floral Compatibility Systems and Pollen Limitation for Prairie Restoration

Ballare, Kimberly M., Stevens, Lee, Jha, Shalene
Rhodora 2017 v.119 no.979 pp. 212-223
Chamaecrista fasciculata, Gaillardia pulchella, Salvia, breeding, ecological restoration, flowering, fruit set, fruits, greenhouses, pollen, pollination, pollinators, reproductive success, seed set, seeds, wild flowers
We conducted a hand pollination experiment to test the effects of supplemental pollen and pollen identity on subsequent reproductive success in three American wildflower species: Chamaecrista fasciculata, Gaillardia pulchella and Salvia coccinea. These species are commonly used in ecological restoration plantings and vary in pollination syndrome and compatibility system. We hypothesized that for all three species, treatments that supplemented pollen would yield greater fruit and seed set. Plants were germinated in a closed greenhouse until flowering, then divided into three treatments: “control”, with no supplemental pollen added; “self”, with supplemented self-pollen; and “outcross”, with supplemented outcross pollen. Treated flowers were bagged and allowed to develop to mature fruit stage, and any resulting fruits and seeds were counted and weighed. Results varied between species. Outcross C. fasciculata flowers had significantly higher fruit set than self or control treated flowers, whereas S. coccinea flowers showed no difference in fruit set between treatments. For S. coccinea, self and outcross flowers tended to produce heavier and more abundant seeds than control flowers, although results were not significant at the p=0.05 level. Gaillardia pulchella produced no fruits or seeds in any treatment. Our results highlight the importance of considering the breeding system and the pollination needs of plants chosen for prairie restorations. If wild pollinators or genetically diverse plant populations are not initially abundant, plantings may need to be monitored or possibly re-seeded for long-term establishment success.