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Friday - February 24, 2012

From: Horseshoe Bay, TX
Region: Southwest
Topic: Grasses or Grass-like, Herbs/Forbs
Title: Native aparejograss and Water-cress at a spring in Horeshoe Bay TX
Answered by: Barbara Medford


AT a small spring that seeps from a rocky hill on my ranch near Austin, a stringy grass called aparejograss has replaced the watercress that used to be there. Should I be worried? Does the appearance of this plant mean the spring in trouble?


Frankly, we had never heard of Muhlenbergia utilis (Aparejograss), but we are familiar with the genus Muhlenbergia. It is a member of the Poaceae (grass) family and grows natively over large parts of the country, including Llano and Burnet Counties. There are several plants with the name "cress" in their common names; one native to North America and Central Texas is  Cardamine pensylvanica (Pennsylvania bittercress).

You can follow either plant link to our webpage on the plant to learn it likes moist, woodland areas and part shade. There was not much information on Cardamine pensylvanica (Pennsylvania bittercress) but we found an article from Illinois Wildflowers that had pictures. It is a member of the Brassicaceae (mustard) family, some of which can become invasive, but we found no indication that this plant does so.

We did considerable searching on spring protection, but could find no research that showed one or another small plant could be a threat to a spring. We all have heard the stories about trees taking over and shutting down spring flows, but this doesn't seem to be the case. Both plants are annuals and it might be that they will rotate the use of the spring, as weather and rain dictates. If you are truly concerned about the invasiveness of the cress, you could hand pull it or make sure it is not permitted to seed out.



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