About Dicerandra frutescens subsp. thinicola (H.A.Mill.) D.B.Ward
Dicerandra frutescens, commonly called scrub mint or scrub balm, is a rare flowering plant in the mint family. It is endemic to the Lake Wales Ridge in Highlands County, Florida, and its native habitat is rapidly being lost to conversion for residential and agricultural use. It was federally listed as an endangered species in the United States in 1985. This shrub grows to roughly half a meter tall from a deep taproot. It is glandular, strongly aromatic with a mint scent. Its oblong leaves are about 2 centimeters long, oppositely arranged, have smooth edges, and are marked with visible oil glands. Its inflorescence is a pair of flowers, each roughly 1.5 centimeters long. Each flower has a tubular throat and a lobed, lipped mouth. The corolla is white to light pink, with darker pink spotting on the lips. Protruding stamens are tipped with tiny horned anthers. It blooms from August through October, and its flowers are pollinated by the bee-fly Exprosopa fasciata. A number of taxa once included within D. frutescens have been split off and raised to full species status: Dicerandra cornutissima in 1981, Dicerandra christmanii in 1989, and Dicerandra modesta in 2008. This subspecies grows in endangered Florida scrub habitat on the botanically distinct Lake Wales Ridge. By 1981, an estimated 74.4% of the native habitat in this region had been destroyed or altered, and habitat destruction continues today. There are 14 known occurrences of the plant, nine of which grow on private property that may be developed; their current status is uncertain, and some occurrences may already have been destroyed. It grows in yellow sand scrub, which may be dominated by sand pine, by a mix of oaks (Quercus spp.) and scrub hickory (Carya floridana), or by both. This type of habitat relies on periodic wildfire to clear large, woody vegetation and create open gaps that smaller plants like this species need to grow. Fire suppression is a major threat to this plant. There is very little disease or predation damage to these plants, though one moth species uses it as a larval host. The aromatic oils of the plant that repel most other insects do not affect the larvae of Pyrausta panopealis. These moth larvae may even protect themselves from other insects by vomiting the plant's irritating oil over their bodies.
