|Cardamine douglassii (04/08/15)|
Durham Co., NC
Cardamine douglassii is sometimes called Limestone Bitter Cress, or Purple Bitter Cress. Neither name seems to be that appropriate (but common names rarely are), First, it only rarely (maybe never?) grows directly on exposed limestone, and certainly never does so in NC. Second, the flowers are rarely purple, but nearly always appear pure white (but see below). For these provincial reasons, I prefer to call it "Douglas's Bitter Cress".
|Douglas's Bitter Cress, |
atypical "purple flower" variant
Granville Co., NC
|Cardamine douglassii habitat in Durham Co., North Carolina|
Bottomland Hardwood Forest, lush cover of Spring Beauty (Claytonia virginica)
04/11/15, Cardamine just finished flowering
Like other Bitter Cress species, Cardamine douglassii is part of the Mustard or Brassicaceae family and produces slender tubular seed capsules, or "siliques", that are much longer than wide.
|Cardamine douglassii in full fruit|
Stems usually lack leaves for most of their length. Several accounts from other states indicate stems are hairy, but I have not observed that in North Carolina. Cauline leaves are usually found on the lower third of the stem, unlobed and usually toothed. Basal leaves are more heart shaped. Younger, non-flowering plants of these perennials produce only rounded leaves
Fortunately, the species seems to require little in the way of active management. Localized threats to populations in North Carolina include construction & maintenance of water and sewer easements. installation of waterfowl impoundments, beaver flooding, and competition with invasive exotics, especially Japanese Honeysuckle.