Fire Pink

Silene virginica
Tuesday, June 17, 2014

            The genus Silene is one of the most well-studied groups to be found on the station. Of the 14 Silene species found in Virginia, nine are found in Giles County—of these, four have been the subject of research in recent years. Although the current Silene lab work focuses on S. vulgaris, the lab has worked with S. latifolia in the past and continues to conduct the annual Silene Census on S. latifoliaS. virginica and S. stellata were both the subject of research by the Dudash-Fenster lab, with a paper on the latter species published just last year.

            Work on S. virginica at the station has focused on traits related to their somewhat unusual pollination system. Ruby-throated hummingbirds, one of their main pollinators, are attracted to the brilliant red color of the flowers. In field studies, the Dudash-Fenster lab found that larger flowers were correlated with a greater nectar reward for the hummingbird pollinators. To determine whether this correlation influences hummingbird behavior, they placed artificial flowers with varying phenotypic traits, but containing equal amounts of nectar and sugar rewards, in the field. They found that “hummingbirds preferentially visited artificial floral phenotypes with larger petal displays, with the greatest preference for floral phenotypes with both larger petals and wider corolla-tube diameters.” A different study by the Dudash-Fenster lab examined the relative importance of the ruby-throated hummingbird in the pollination of S. virginica. When the flowers were caged to allow access only by insect pollinators, they had a lower seed set than the control plants (which were accessible to hummingbirds) in all but one year of their study. They concluded that even in the presence of invertebrate pollinators, hummingbirds may still be responsible for most of the pollination that occurs because of their efficiency at pollen transfer. In addition, because of the dependency of S. virginica on the single species of pollinator, “it is likely that hummingbirds are the most important selective agent responsible for the evolution and maintenance of…floral traits associated with the hummingbird pollination syndrome.”

            S. virginica are striking perennials, sometimes planted for landscaping purposes or in gardens. In the wild, they can be found in meadows, open, rocky slopes, and rich to dry woodlands. They typically reach 15-60 cm. in height. Basal leaves are often smaller than the leaves found on the stem, which appear in pairs and can reach 15 cm in length. The plants are also sometimes given the name “catchfly” because of the sticky hairs which coat parts of the stems, the upper leaves, and the inflorescences and can trap small insects which land on them.

            Although their blooms are short-lived, fire pinks are conspicuous plants that can be found in flower near mid-summer at MLBS. Elsewhere in their range, blooms can occur as early as April or as late as August. They can be found across most of the eastern half of the country, except for the far north-eastern states. In suitable environments, they are relatively common; however, they are considered rare in many locales near the edge of their range. This cutting was taken near Reed, where a number of the plants are growing on the south-facing slope behind the cabin.

Hazel Galloway