Shale Barren Rockcress

Description

Arabis serotina is a rare species of flowering plant in the mustard family known by the common name shale barren rockcress. It is native to eastern West Virginia and western Virginia in and around the Shenandoah Valley, where it is known from fewer than 60 populations. It is endemic to the shale barrens, a type of habitat characterized by steep slopes of bare shale, an exposed, rocky habitat type that is subject to very dry and hot conditions.Shale barrens host a number of endemics, such as Allium oxyphilum and Taenidia montana, and this rockcress is among the rarest. It is a federally listed endangered species.This is a biennial herb which has a small, inconspicuous basal rosette of leaves measuring a few centimeters wide. It bolts with an erect, branching stem that can reach a maximum height near one meter. Leaves along the stem may be 5 to 15 centimeters long, lance-shaped, and sometimes toothed along the edges. Leaves wither early, and the plant may have few or no leaves at flowering. The inflorescence is a raceme of several tiny white flowers each under a centimeter wide. The fruit is a silique measuring 4 to 8 centimeters in length and containing many small seeds.