Calyptridium is a genus of plants common in montane regions across the west coast of North America, often seen growing in disturbed areas along paths or in open clearings with sandy soils. Two species in particular (C. monospermum and C. umbellatum) are especially well known for vertically raising their peduncle (the main stalk of the compound inflorescence) throughout the day. Calyptridium monospermum plants raise their peduncles in the middle of the day when in full sun and rest them on the ground in the shade or night (Osleger, unpublished data). Despite the notability of these species’ movements by hikers and botanists alike, neither the main stimulus for this action nor its effect on plant fitness have been investigated. We plan to conduct a series of studies that will determine both the stimulus for inflorescence movement in C. monospermum, and how this action may affect fitness. We will perform two longer term studies throughout the species’ flowering phenology. The first will identify whether temperature, light or humidity has the largest effect on peduncle angle. The second will measure the effect of light availability and peduncle angle on plant fitness. We will also conduct a shorter term pollination study to identify how inflorescence movement may relate to increased pollination under certain environmental conditions.

Approved