Examination of Stylar Movement Among Floral Morphs in Passiflora incarnata L.

Abstract

Passiflora incarnata is a widespread vine that is native to the Southeast United States and is most common in open sunny habitats along roadsides, riverbanks, thickets, and abandoned agricultural fields. It is also an important larval host plant to several species of butterfly and is pollinated primarily by carpenter bees. This species experiences a range of stylar movement after the flower opens in the beginning of the day, of which have been categorized into five different morphs based on their position at the end of the day. Relatively little is known about the stylar movement expressed in Passiflora incarnata. To further study the tissues involved in this movement, various specimens were observed using light microscopy. We focused our attention on the ovary apex junction, examining the transmitting tissue and vascular bundles as they move down the style and into the ovary. On the most functional and abundant morph, we saw inflated cells on the abaxial side of the ovary apex junction, and deflated cells on the adaxial side; this leads us to suspect that an osmotic process is responsible for the movement. Several samples have been taken before and after the stylar movement to better understand the tissue structures and are currently being observed.