Plant of the Week
Platanthera obtusata range map. USDA PLANTS Database.
In this image from Michigan the very uncommon Trillium grandiflorum forma roseum is present with a pair of the white-flowered Trillium grandiflorum. Image with permission by Charles Peirce.
Coming across a flowering Trillium grandiflorum in spring time is a real treat. It has a most spectacular bloom. Image with permission by Charles Peirce.
We can readily see why this native wildflower was given the genus name Trillium referringto the petals, sepals, and bracts (generally called leaves by most people) occurring in groupings of three. Image with permission by Hugh & Carol Nourse.
This great white trillium is infected with a mycoplasma that causes greening in the petals. This mycoplasma is parasitic on great white trilliums. Image with permission by Charles Peirce.
This multi-petaled great white trillium is referred to as Trillium grandiflorum f. polymerum. Image with permission by Charles Peirce.
Trillium grandiflorum var. roseum. Photo by Kevin Taylor.
Trillium grandiflorum. Photo by Gayle P. Clement.
Great White Trillium (Trillium grandiflorum)
By Larry Stritch
The great white trillium is an herbaceous, long-lived, woodland, perennial wildflower with a broad distribution in eastern North America. This trillium occurs on well-drained, rich, mesic soils in deciduous or mixed deciduous/coniferous forests. Great white trillium occurs from southern Quebec and Ontario and then Maine west to northeastern Minnesota; through the central hardwoods to the Appalachian Mountains and thence south on the southern Appalachian Mountains to Georgia.
Great white trillium generally occurs in spectacular drifts of dozens, to hundreds, and to thousands of individuals. In the Blue Ridge Mountains of northern Virginia along the Appalachian Trail there is a spectacular display of great white trilliums estimated at near ten million individuals.
Fred and Roberta Case, in their book Trilliums, describe the innate beauty of great white trilliums, “This species, the most showy, best known, and loved of all the trilliums…”
Trillium grandiflorum (Trillium – from the Latin tri referring to the flower parts occurring in threes, and llium from the Latin liliaceous referring to the funnel-shaped flower and grandiflorum – from the Latin grandis – great, large and Flora - goddess of flowers) referring to the large white flower.
Trilliums are generally divided into two major groups, pedicellate and sessile. In the pedicellate trilliums, the flower sits upon a pedicel that extends from the whorl of bracts, either “erect” above the bracts, or “nodding” recurved under the bracts. In the sessile trilliums there is no pedicel and the flower appears to arise directly from the bracts. Great white trillium falls within the pedicellate group.
Trillium grandiflorum has a short, thick rhizome from which a sheath (cataphyll) enclosed scape (stalk of the inflorescence) emerges from the ground to15 to 45 centimeters tall with a single, terminal flower on an erect pedicel, 2 to 10 centimeters long; leaves (actually bracts) three, dark green, sessile to sub-sessile, round-ovate to sub-rhombic, acuminate, 10 to 30 centimeters long and 8 to 15 centimeters wide; petals three, white (fading to pink) oblong, 4 to 7 centimeters long, recurved at the middle to form a very funnel-shaped corolla; sepals three, green, dark green streaked with maroon, or occasionally dark maroon, acuminate, flat, spreading, 2.5 to 5 centimeters long; fruit a berry, pale green, ovoid, six-angled, brown seeds.
Trillium grandiflorum flowers from late April to early June (dependant on latitude and elevation). The species occurs in a range of habitats in rich deciduous or mixed coniferous-deciduous woods.
There are a number of green/white forms that represent various stages in the development of a mycoplasma infection. There is a very beautiful and striking rose-pink colored flower that occurs rarely but is encountered frequently in mixed populations (rose-pink and white) along the Blue Ridge Mountains in Virginia.
White-tailed deer and their increasing numbers are adversely affecting great white trillium populations through repeated grazing.
For More Information
- PLANTS Profile - Trillium grandiflorum, great white trillium
- Trillium grandiflorum in Flora North America.
- Case, F. W. and R. B. Case. 1997. Trilliums. 284 pp. Timber Press. Portland, Oregon.
- Jacobs, D. L. and Jacobs R. L. 1997. Trilliums in Woodland and Garden: American Treasures. 152 pp. Eco-Gardens. Decatur, Georgia.
- Patrick, T. 2007. Trilliums of Georgia. Tipularia 22: 3-22. Georgia Botanical Society.
- Frett, J. 2007. Trilliums at Mt. Cuba Center: A Visitor’s Guide. 75 pp. Mt. Cuba Center, Inc. Greenville, Delaware.