aka Large-Flower Valerian

Valeriana pauciflora; Valerianaceae (valerian family)

Listed as threatened in the state of Maryland.  Yesterday I found a third healthy stand in the greater Carderock area.  One of the things I like about this plant is that each pair of opposite, compound leaves is oriented on the stem 90 degrees away from the next pair.  And the flowers are lovely, too.