Mode of Pollination, Pollen Germination, and Seed Set in Smooth Cordgrass (Spartina alterniflora, Poaceae)

Spartina alterniflora, a perennial grass dominating the salt marsh in tidal wetlands, is used extensively to prevent soil erosion and restore wetlands along the Atlantic and Gulf coasts of North America. Controlled crossing is required to develop S. alterniflora populations with improved reproductive and vegetative characteristics that enhance restoration potential. Spartina alterniflora accessions collected from Louisiana salt marshes were used to investigate methods of pollination by examining pollen germination, pollen tube growth, and seed set following selfing or cross‐hybridization. Fluorescent microscopy was used to observe pollen germination and pollen tube growth at different time intervals following pollination. Anthesis occurred primarily between 0800 and 1000 hours. Pollen was viable, with average germination of 52% and 67% following self‐ and cross‐pollination, respectively, and stigmas were receptive after exsertion from the floret. Pollen germinated about 15 min after contacting the stigma, and pollen tubes grew to the micropyle within 55 to 75 min. Spartina alterniflora exhibited protogynous flowering where stigmas protruded from the floret 2–5 d before anthesis. Average seed set under self‐ and cross‐pollination was 26% and 52%, respectively. These findings indicate S. alterniflora is largely cross‐pollinated and that protogyny can be exploited to make controlled hybrids for genetic research and improvement. These findings have ecological and practical implications for salt marsh restoration and maintenance.