SEED PRODUCTION IN GENTIANA-NEWBERRYI (GENTIANACEAE)

Experimental manipulations and observations in one population of Genti ana newberryi Gray flowers over 2 years showed significant variation i n seed production relative to pollinator and soil water availability. When pollinators were rare, there was a significant relationship betwe en number of bees present and number of mature seeds produced, and sup plemental hand cross-pollination (xenogamy) did improve seed set in Ge ntiana newberryi Gray. When pollinators were abundant, supplemental ha nd cross-pollination did not increase seed set. Self-fertilized seeds (autogamy) germinated at the same rate as cross-pollinated seeds. Seed production in unvisited flowers is probably limited anatomically and is not influenced by the type of fertilization. There was a significan t relationship between soil moisture and flower size in G. newberryi, with larger flowers found in wetter areas.