Tuesday, March 16, 2010

Hairy Bittercress (Cardamine hirsuta)

I spotted the characteristic rosettes of Hairy Bittercress (Cardamine hirsuta) by the pool at the creek on January 10th. At first I mistook them for Shepherd’s Purse (Capsella bursa-pastoris) although the rosette of this plant is distinctly different.

These plants led a hard life. They were submerged under a couple of inches of water for a couple of days in two successive rounds of flooding. In this photograph, you can see plants just starting to bloom (white spots).

The plants maintained their rosette shape for some time. At first a single flower spike develops.

Then they send up several flower spikes and the plant loses its distinct rosette shape and becomes more ‘bushy.’

The flower petals open up for a short time.

More often the flower petals appear to ‘close’ as seedpods develop. The leaves on the flower stalks are quite different from the rosette leaves.

Ultimately the plants appear to be a cluster of bare stems. The flowers are almost invisible among the forest of stems.

Hairy Bittercress was introduced from Europe and is considered a weed, distribibuted throughout the Unites States and Canada, and difficult to eradicate. I’m not sure that I mind. In addition to finding it at home, I have found them on the lake side of the dam as well as on the plateau between the pedestrian bridge and the gas line in Fort Yargo State Park.

Click on an image to view a larger image

Identification resources:

- Shedi de botanica: Cardamine hirsuta – Hairy Bittercress
- Shedi de botanica: Capsella bursa-pastoris – Shepherd’s Purse

- Cardamine hirsuta

Related posts:

- Whitehall Lake: Wildflowers

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