Experimental manipulations and observations in one population of Gentiana newberryi Gray flowers over 2 years showed significant variation in seed production relative to pollinator and soil water availability. When pollinators were rare, there was a significant relationship between number of bees present and number of mature seeds produced, and supplemental hand cross-pollination (xenogamy) did improve seed set in Gentiana newberryi Gray. When pollinators were abundant, supplemental hand 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 significant relationship between soil moisture and flower size in G. newberryi, with larger flowers found in wetter areas.
Barnes, Myra E. and Rust, Richard W.
"Seed production in Gentiana newberryi (Gentianaceae),"
Great Basin Naturalist: Vol. 54
, Article 7.
Available at: http://scholarsarchive.byu.edu/gbn/vol54/iss4/7