Monday, April 25, 2011

An Unusual Trillium

Toadshade, or Toad Trillium, or Sessile Trillium (Trillium sessile) is a common woodland flower in southern Ohio. Although some may not recognize it as a trillium, it has the same three petals, three sepals, and three whorled leaves.

But wait – this one looks a little odd. That’s because it isn’t the usual Trillium sessile, but Trillium recurvatum – Prairie Trillium. It has the same upright maroon petals, and the same mottled leaves. Here’s a T. sessile for comparison.

There are two main differences. The leaves are not sessile, but petiolate. In English, they aren’t attached directly to the stem (sessile), but instead have petioles, or stalks (petiolate). And the sepals (the small green triangles at the base of the flower) droop below the petals, instead of rising along with the petals – they are curved backward – recurved.

A less obvious, and more variable, difference is that T. recurvatum tends to be taller, with the leaves and flower being held farther off the forest floor.

T. recurvatum shares the same habitat as T. sessile – rich forest floors. The “prairie” in its common name is misleading – it does not occur in prairies. It is basically a midwestern species. It is common in Indiana, but its range barely extends into western Ohio, where it is considered to be a Threatened species.

So when you're walking through the woods of western Ohio in April, take a closer look at those ordinary Toadshades, and maybe you'll find a much rarer plant.


  1. Great post, Ned! I saw quite a bit of that in full bloom in SE Indiana a couple weekends ago on botanical excursion with Dan Boone. Even got the chance to snap some photo's of the yellow flowered form. Looking forward to seeing you this weekend at Flora-Quest!

  2. Wow! I need to look a little more closely at my Sessile Triliums. I think I may have misidentified some Prairie Triliums in the past.

    thanks for the tips.


  3. Neat Trilliums! Just if anyone is wondering, they both seem to be totally hardy here in Ontario, Canada. I'm in zone 4 and have several T. sessile and T. recurvatum plants and they are doing quite well. They'll be in bloom in another week or two - we of course have Spring a little later than you do!