Eriocaulon parkeri B. L. Robinson is a monoecious, pioneer species of tidal mudflats that displays
characteristics that suggest outcrossing as a preferred breeding system. Analyses of breeding system
dynamics, fruit set, and pollen and seed viabilities were undertaken in Connecticut andWisconsin to
test the hypothesis of entomophyly and outcrossing as a preferred breeding strategy. Potential
pollinators included syrphid and long-legged flies. Seed viability was estimated at 94 16%
(n = 133); pollen viability at 88 13%. Pollen production averaged 500 grains per flower.
Pollen–ovule ratios within inflorescences averaged 196:1, suggesting facultative autogamy. Seed
set in natural populations averaged 74%, not significantly different between early and late season
plants or between greenhouse controls and hand pollinations. Emasculated plants produced small
amounts of seed under controlled greenhouse conditions. Pollen tube growth through the styles of
E. aquaticum, a related species, was much more prevalent than that of E. parkeri. Results suggest that
E. parkeri relies heavily on geitonogamy for seed production. Some seed may be produced by
agamospermy.