Thursday, March 25, 2010

Is It Chickweed?

Let's take a look at those white-flowered weeds in the lawn right now.  Chickweed, right?  Well, yes and no.  In Piedmont gardens there are at least two plants called chickweed, Stellaria media (common chickweed), and Cerastium glomeratum (mouse ear chickweed).  There are many other chickweed species, but these are common here. Cardamine hirsuta, commonly called bittercress,  is in a different plant family entirely but is frequently confused with the chickweeds because it grows intermingled with them.


Here are my unscientific but practical tips which will help you determine which plant you have:

When did it first appear in your lawn?  Bittercress (Cardamine) shows up earliest by a few weeks, followed by the chickweeds - Stellaria, then Cerastium.  There is probably some deviation, but most years that's the order. If you don't know for sure when it began to pop up, how about this -

Bittercress stands well above the grass within a short while after mowing.  Chickweeds hug the ground more and spread horizontally faster. 

For a more scientific tip: The best clue that you have bittercress is the seed capsules (siliques) that begin to show up after blooms fade.  They stand erect, are about a half inch long and have little bumps in them where the seeds are forming.  You can see them from several feet away.  Chickweed does not form these at all. 


You will probably want to remove these plants from your lawn, but you might consider eating them. Bittercress and Chickweed are both edible salad plants. Just be sure they haven't been sprayed with herbicides during the past few weeks!

More details for the botanically curious: 

Check the growth habit.  Do the leaves form a basal rosette (bittercress), or are the leaves all along the stems and do they root where the stem nodes touch the ground (chickweed)?  Chickweed leaves are entire and bittercress leaves are pinnately divided.

How about the flowers?   Chickweeds are are in the carnation family, Caryophyllaceae.  The flowers have 5 petals.  In Stellaria each petal is divided so that the flower appears to have 10 petals.  Cerastium's 5 petals are cleft, but not so divided they look like 10. (You might need a magnifier to check this one out.)  For both chickweed genera, the leaves grow oppositely on either side of swollen nodes (think of a carnation stem).  Cardamine is in the mustard family, Brassicaceae, like broccoli, cabbage and nasturtium.  The flowers typically have four petals and four sepals.

Virginia Tech's very useful Weed Identification Guide has and ID key, pictures of common weeds at various stages of their life cycles, and listings by scientific and common names.

vPlants's comprehensive plant glossary defines terms with "special meaning in a botanical context".

More References
Manual of the Vascular Flora of the Carolinas by Radford, Ahles and Bell, University of North Carolina Press, 1968

Botany Illustrated by Glimn-Lacy and Kaufman, Chapman and Hall, 1984

Edible Wild Plants - Peterson Field Guides #23 by Lee Allen Peterson, Houghton Mifflin Company, 1977


1 comment:

  1. Good explanation!! My friend has chickens and they love chickweed but not the bittercress. Weed ID is good to know...just ask the chickens ;-)