The Distribution and Life History of the Trillium nivale Riddell

The Trillium nivale, commonly called the Snow Trillium, is the earliest of the vernal wild flowers in Iowa and probably throughout its range (Fig. 1). Records kept over a period of years at the Ledges State Park in Boone County, Iowa, show that the Snow Trillium begins flowering in that vicinity between the 10th and 25th of March. At its northernmost limit it is in full flower during April. Its ability to develop and flower under low temperatures is one of its remarkable features. The ground is still partly frozen or barely thawed about its corm when the Snow Trillium sends up its shoot and opens its flower. Sometimes its flowering shoot in an apparent thrifty condition can be found protruding through a blanket of snow. It is often caught when in flower by temperatures several degrees below freezing which it seems to endure without injury