From moths to microbes: investigating reproductive biology, pollination and nectar in Platanthera Transversa (Suskd.) R.M. Bateman (Orchidaceae)

Platanthera transversa is a common orchid in western North America yet it is poorly studied. This makes it difficult to understand the breadth of pollinators and floral attractant mechanisms present, both of which are vital to understanding the dynamics of its pollinator interactions and fecundity as well as floral evolution. Continuous video capture, hand-pollination, and bagging experiments were used to identify pollinators and determine if self-pollination was possible. Nectar volume and composition were assessed, and culturable nectar bacteria were identified by sequencing the 16S rRNA region from pure isolates. We found two moth pollinators and an absence of self-fertilization when pollinators were excluded. Nectar volume was highest in the morning. Microbial species richness in nectar was low overall, but highest in the older flowers. Our study provides a comprehensive assessment of pollination and nectar in P. transversa, identifying several future research themes that could advance our understanding of plant-pollinator-microbe systems.