This section is from the book "Nature's Garden", by Neltje Blanchan. Also available from Amazon: Nature's Garden; An Aid To Knowledge Of Our Wild Flowers And Their Insect Visitors.
Calyx of 3 spreading sepals, 1 to 1 1/2 in. long, or about length of 3 pointed, oval petals; stamens 6; anthers longer than filaments; pistil spreading into 3 short, recurved stigmas. Stem: Stout, 8 to 16 in. high, from tuber-like rootstock. Leaves: In a whorl of 3; broadly ovate, abruptly pointed, netted-veined. Fruit: A 6-angled, ovate, reddish berry.
Preferred Habitat - Rich, moist woods.
Flowering Season - April - June.
Distribution - Nova Scotia westward to Manitoba, southward to North Carolina and Missouri.
Some weeks after the jubilant, alert robins have returned from the South, the purple trillium unfurls its unattractive, carrion-scented flower. In the variable colors found in different regions, one can almost trace its evolution from green, white, and red to purple, which, we are told, is the course all flowers must follow to attain to blue. The white and pink forms, however attractive to the eye, are never more agreeable to the nose than the reddish-purple ones. Bees and butterflies, with delicate appreciation of color and fragrance, let the blossom alone, since it secretes no nectar; and one would naturally infer either that it can fertilize itself without insect aid - a theory which closer study of its organs goes far to disprove - or that the carrion-scent, so repellent to us, is in itself an attraction to certain insects needful for cross-pollination. Which are they? Beetles have been observed crawling over the flower, but without effecting any methodical result. One inclines to accept Mr. Clarence M. Weed's theory of special adaptation to the common green flesh-flies (Lucilia carnitine!), which would naturally be attracted to a flower resembling in color and odor a raw beefsteak of uncertain age. These little creatures, seen in every butcher shop throughout the summer, the flower furnishes with a free lunch of pollen in consideration of the transportation of a few grains to another blossom. Absence of the usual floral attractions gives the carrion flies a practical monopoly of the pollen food, which no doubt tastes as it smells.
The Sessile-flowered Wake-Robin (T. sessile), whose dark purple, purplish-red, or greenish blossom, narrower of sepal and • petals than the preceding, is seated in a whorl of three egg-shaped, sometimes blotched, leaves, possesses a rather pleasant odor; nevertheless it seems to have no great attraction for insects. The stigmas, which are very large, almost touch the anthers surrounding them; therefore the beetles which one frequently sees crawling over them to feed on the pollen so jar them, no doubt, as to self-fertilize the flower; but it is scarcely probable these slow crawlers often transfer the grains from one blossom to another. A degraded flower like this has little need of color and perfume, one would suppose; yet it may be even now slowly perfecting its way toward an ideal of which we see a part only complete. In deep, rich, moist woods and thickets the sessile trillium blooms in April or May, from Pennsylvania, Ohio, and Minnesota southward nearly to the Gulf.