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Trillium cernuum (nodding trillium, northern nodding trillium, nodding wakerobin, or whip-poor-will flower) is a species of flowering plant in the family Melanthiaceae. It is the most northerly occurring species of Trillium in North America, occurring as far north as Hudson Bay. Its range extends across Canada, from Saskatchewan in the west to Newfoundland in the east, and as far south as northern Virginia. It occurs on rich, moist soils in both broadleaf and coniferous woodland.
It is a perennial herbaceous plant with one or more unbranched stems 15–60 cm (6–24 in) tall growing from an underground rhizome. The apex of each stem has whorl of three abruptly pointed bracts 4–15 cm (1 1⁄2–6 in) long and 6–18 cm (2 1⁄4–7 in) broad, and on strong stems, also a solitary flower hanging below the leaves on a 0.5–3.5 cm (1⁄4–1 3⁄8 in) peduncle. The flower is perfect, with three slender pale green sepals 9–30 mm (0.35–1.18 in) long, three broad white (rarely pink) petals 15–25 mm (5⁄8–1 in) long and 5–15 mm (1⁄4–5⁄8 in) broad, six purple stamens, and a solitary pistil; flowering is in late spring to early summer. The fruit is a six-lobed reddish berry up to 3 cm (1 1⁄4 in) in diameter, ripening in late summer.
- "Trillium cernuum". NatureServe Explorer. NatureServe. Retrieved May 3, 2008.
- "Trillium cernuum". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
- Case Jr., Frederick W. (2002). "Trillium cernuum". In Flora of North America Editorial Committee (ed.). Flora of North America North of Mexico (FNA). 26. New York and Oxford. Retrieved September 24, 2007 – via eFloras.org, Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
- Stritch, Larry. "Northern Nodding Trillium (Trillium cernuum)". United States Forest Service. Retrieved 1 July 2019.
- "Trillium cernuum". Northern Ontario Plant Database. Retrieved September 24, 2007.
- "Trillium cernuum". Native Plant Database. Lady Bird Johnson Wildflower Center, University of Texas at Austin. Retrieved August 5, 2010.
- "Trillium cernuum". Intermountain Herbarium. Archived from the original on 2007-07-23. Retrieved September 24, 2007.
- "Trillium cernuum". Boreal Forest. Retrieved September 24, 2007.
- "Rare Plants of Ohio". ODNR Division of Natural Areas and Preserves. Retrieved 4 September 2019.