Plants, pollinators and their interactions result in ecological services that sustain diverse natural communities as well as agricultural systems. Understanding the timing of plant-pollinator interactions in varied habitats influences the predicted effect of changing climatic conditions on successful reproduction by both partners. In North America, Camassia species (camas "lily") are important spring-flowering geophytes in environments ranging from summer-dry vernal pools and lowland oak savannas to forest glades or isolated montane fens. The timing of floral opening, the associated pollinator faunas, and visitor access to camas flowers have been little studied, despite the high cultural-conservation value of Camassia and its close ties to soap root (Chlorogalum), rush “lilies” (Hastingsia), and other Agave relatives. This study used marked individuals, plots and transects to assess pollinator visitation and importance under differing ecological contexts. Also, plants and flowers were experimentally manipulated to track floral opening and life span, linking these to floral traits and a fauna that is conventionally understood to consist of largely generalist, diurnal pollinators. As possible, floral opening and visitation patterns were examined for other flowering plants in these communities.
Results/Conclusions
Camassia species, studied in multiple populations, varied less in the timing of floral opening than in floral life span, revealing new insights about vespertine pollination, particularly in the rare C. howellii. Flower number per raceme and the synchrony of flowering differed for species and populations as well. Across multiple species and in diverse ecological, elevational, and geographic contexts, the most common visitors were diurnal bee pollinators, wasps, and syrphid flies. Hawkmoths, butterflies, and beetles were uncommon, with large bees (Apidae) ranking as most effective but varying markedly in the timing and context of their visitation. Our results have implications that appear strongly linked to habitat, and they imply that communities of pollinators on different plant species need more study across single flowering seasons and among years.