One of the reasons for greater plant diversity in the deciduous hardwood forests of eastern North America compared to the coniferous forests of the Pacific Northwest is light penetration to the forest floor. If you've hiked some of the old growth or second growth coniferous forests in British Columbia, you'll know that there can be very few plants growing beneath the trees throughout the year, perhaps only the occasional saprophytic orchid or straggly huckleberry.

This photograph, taken in the deciduous forest of the Old Baldy Conservation Area along the Niagara Escarpment in Ontario, illustrates the opposite. In early spring, before the trees have fully leafed out, the first wave of perennials grow and flower, such as these large-flowered trilliums (more on trilliums). Later in the year, summer sunlight dapples the forest floor, and another wave of flowers bloom. Finally, as the tree leaves colour and begin to fall, asters and goldenrods flower to complete the annual parade of herbaceous colour.

Sam Roberts, also the photographer of Conopholis americana from last week, contributed this photograph. I've set up an area in the garden's discussion forums for Botany Photo of the Day Reader Submissions, if you are a participant on the forums. If you would like to contribute using Flickr instead, I'm still in the process of setting that up (thank you and apologies to Jennifer, who kindly emailed me with an offer of help last week - I'm sorry I haven't replied yet, but I'll be in touch soon!).

Update (June 1, 2005 2:40 AM PST): The latest edition of the Tangled Bank is out, Tangled Bank #29, and it features the Botany Photo of the Day entry on Kadsura interior. For those of you who aren't familiar with Tangled Bank, it is a semi-weekly showcase of science-based writing in weblogs, hosted by a different weblog every edition. It's a great way to discover other weblogs, and well worth a visit.