An older scientific name for Virginia Rock Cress is Arabis virginica. It has since been reassigned to its own genus, Sibara, which is simply 'Arabis' spelled backward. This is one of the few annual plants in the Mustard family that is native to North America, rather than introduced from Eurasia. The species in this large family are often hard to tell apart. Like the similar Arabis spp. (Rock Cresses), Virginia Rock Cress has white flowers with 4 petals, siliques without stipes or beaks, and seeds with winged margins. It differs from the Rock Cresses in being a rather weedy annual plant rather than a more conservative perennial. Some distinctive features of Virginia Rock Cress include the tiny size of the flowers (only 1/10" across) and its deeply pinnatifid leaves. It is glabrous, except for a few hairs at the base of the flowering stems, and its siliques are semi-erect. Other Rock Cresses tend to have larger flowers and hairier leaves that are less deeply lobed. Their siliques may be appressed close to the flowering stalk like Arabis glabra (Tower Mustard), or they may be widely spreading and rather floppy like Arabis canadensis (Sicklepod).