Plant of the Week

Trillium persistens, persistent trillium, range map.
Trillium persistens range map. USDA PLANTS Database.

Trillium persistens, persistent trillium.
Trillium persistens. Photo by Hugh Nourse.

Closeup Trillium persistens flower.
Trillium persistens. Photo by Hugh and Carol Nourse.

Trillium persistens, persistent trillium.
Trillium persistens. Photo by J. D. Freeman, courtesy of Smithsonian Institution.

Persistent Trillium (Trillium persistens)

By Mark Pistrang

All trillium species belong to the Liliaceae (lily) family and are rhizomatous herbs with unbranched stems. Trillium plants produce no true leaves or stems above ground. The “stem” is actually just an extension of the horizontal rhizome and produces tiny, scalelike leaves (cataphylls). The above-ground plant is technically a flowering scape, and the leaf-like structures are actually bracts subtending the flower. Despite their morphological origins, the bracts have external and internal structure similar to that of a leaf, function in photosynthesis, and most authors refer to them as leaves.

Trilliums are generally divided into two major groups: The pedicellate and sessile trilliums. In the pedicillate trilliums, either the flower sits upon a pedicel that extends from the whorl of bracts “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.

Known from only a few locations in Georgia and South Carolina, persistent trillium was listed as Endangered by the U.S. Fish and Wildlife Service in 1978. This pedicillate trillium blooms from early March through mid-April and occurs on organic soils in mixed deciduous-pine woodlands, along stream flats and at edges of Rhododendron thickets. Once featured on a U.S. postage stamp, this species is of high conservation concern and all sites should be protected. Take only pictures; let us keep this trillium persistent!

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Wheel milkweed, Asclepias uncialis.
Wheel Milkweed (Asclepias uncialis)