The effects of pollination distance on seed production in three populations of Amianthium muscaetoxicum (Liliaceae)

Summary We examined the effects of varying pollination distances on seed production and its components in three populations of the perennial lily Amianthium muscaetoxicum. We performed hand pollinations using pollen from near neighbors and from plants separated by 5, 15, and 60 meters. Pollination by near neighbors reduced fruit set and the numbers of seeds per fruit in comparison to other treatments in two of the three populations; variation in pollination distance beyond near-neighbor pollination produced no effect. In the third population, in which nearneighbor pollination did not affect seed production, nearneighbor pollination reduced seed weight by 11%, compared to other pollination distances. Seed weights from the 5-, 15-, and 60-m pollination treatments did not differ, and pollination distance did not affect seed weight in the other two populations. The effects of pollination-distance treatments explained a very small proportion of the variance in seed production and seed weight. Heterogeneity among individual plants, despite full hand pollination of every plant, accounted for much more variance (by one to two orders of magnitude) than variation in pollination distance.