A quick stroll around the Carderock area and Billy Goat B up to the Marsden Tract on March 9 showed that the flowers are only just starting. I saw a fair number of spring beauties (Claytonia virginica), a few cut-leaved toothworts (Cardamine concatenata), and one clump of Virginia bluebells (Mertensia virginica) in bloom.
Harbinger-of-spring (Erigenia bulbosa) looks like it’s at its peak, though. There are a few really solid stands of it near the river, but they are hard to find if you aren’t looking closely, since an entire plant is about the width of a nickel.
I was a bit surprised to find lyre-leaved rock cress (Arabidopsis lyrata) open already, though most plants had more buds than blossoms. Look for it growing right out of rocks near Carderock.
Elizabeth's Wildflower Blog 