Allelopathy in pussy toes (Antennnaria sp.)

The production by plants of chemicals that inhibit growth of other plants is called allelopathy, and is surprisingly common. Among species that exhibit this phenomenon are those of the genus Antennaria (pussy toes).

We have two species of Antennaria at Pleasant Valley Conservancy, A. neglecta and A. plantaginifolia, both of which exhibit this phenomenon. They form compact mats which are virtually monospecific, which is a good indication of the presence of allelopathy.

We have several sites at Pleasant Valley in open woodlands where relatively large Antennaria mats are present. The photo above is from a mat at Unit 13A, in an open area adjacent to a white oak woodland. This site had been invaded by aspen, and Kathie and I removed that clone by girdling about 8 years ago. The Antennaria mat probably developed after the aspen were removed.

This site is slowly being converted to prairie. Indian grass is moving in (you can see a small clump in the lower right hand corner of the photo at top), and there are lots of forbs. In fact, I was collecting gray goldenrod (Solidago nemoralis) seeds when I noticed this pussy toes mat. As the smaller photo shows, it is a very compact mat and is almost a pure stand.

I did a literature search for details on Antennaria allelopathy, and found surprisingly little information, although many web sites mention that Antennaria exhibits this trait (without citations).

Of interest is that Antennaria is dioecious (has separate male and female plants).