Tuesday, April 12, 2011

Leavenworthia Thicket

I guess you really can’t call it a thicket when the plant in question only gets a couple of inches high, but it’s what I think of when I see the tiny Leavenworthia uniflora covering the landscape. On a given site, the numbers of this winter annual can vary considerably from year-to-year. Blue Jay Barrens has several populations of Leavenworthia. Some of those are low in number this year, but others have appeared in record numbers.
Leavenworthia uniflora grows in areas of shallow, mostly bare soil over limestone bedrock. The seeds germinate in late fall or early winter and a couple of tiny leaves nourish the developing tap root during the winter months. The deep taproot is necessary to help keep the plant in place during frost heaving of the soil and other winter hazards. In early spring, the priority shifts to leaf and then flower production. The plant will die after producing seeds, so there’s no need to store energy for the future. All energy produced is used to produce a crop of seeds for next year.

A little bit of dead plant matter on the soil seems to help protect the developing plant. However, if the residue is heavy, the plant doesn’t seem to get enough sunlight to survive.

A dry limestone ridge provides ideal growing conditions for Leavenworthia. The clumps of grass growing around the bare spots seem to afford just the right amount of protection.

The flowers are quick to produce fruits referred to as silques. Each silque may contain a dozen or more large seeds. The seeds require a period of heat to prepare them for germination. They get all the heat they need as the ridgetop bakes in the summer sun. When cool, damp conditions return, the seeds are ready to grow. The seeds are very easy to germinate, but the plant remains a rarity in most areas. Even when there is apparently suitable habitat nearby, the plant is slow to exploit the potential new range. I suppose there’s a reason for this that I have just not yet discovered.


  1. Hi Steve..I sure am having a devil of a time keeping up these days..
    Cute little thing this plant.
    So many tiny plants that we walk on everyday, and then one day they are gone..
    Nice that there are people like you who care about this!!

  2. Hi, grammie g. It's nice to get belly down in the field and look at all of the tiny things that are normally not seen. Don't do it near the road though, because everyone will stop and try to rescue you.