Thanks to LW’s comment on my recent post about toothworts, I was finally able to see a good-sized stand of Cardamine bulbosa, also known as spring cress, bulbous bittercress, or bulbous toothwort.
This species is a wetland obligate; here you can see it almost standing in the water of a vernal pond.
The cauline (stem) leaves are entirely different from the slender and cut-leaved toothworts’.
The flowers and inflorescence look much like the toothworts, though. Another Cardamine species found in Maryland, limestone bittercress (C. douglassii), is almost identical to spring cress, but it species has hairy, dark purple sepals rather than the smooth, green sepals seen here.
Spring cress is native to the eastern US, where it ranges from Florida to New Hampshire (where it’s endangered) and into the Great Plains from Texas to Minnesota.
Some of your plants look so familiar to plants that I can not identify here that I sometimes wonder if they were brought here like so many of the other invasive exotic specie. Even if they were not brought for herbal medicine or for vegetable gardening, they could have been brought unintentionally.