Kingdom: Plantae

Phylum: Magnoliophyta -- flowering plants

Class: Liliopsida -- monocotyledons

Order: Liliales

Family: Liliaceae -- lily

Subspecies: The Palouse phase is ssp. ovatum

Common Name: white trillium, Pacific trillium, western wake-robin

Species Code: TROV2

Origin: Native to open to dense coniferous forests of western North America from British Columbia to California east to Idaho, Montana, Wyoming, and Colorado.

Rare: no

Form: forb, perennial, from a fleshy horizontal to semi-erect rhizome, 10-30 cm tall, glabrous.

Mature height: 4-12 inches

Duration: perennial

Habitat Type: forest, hawthorn thicket

Wetland Indicator Status: FACU

Leaves: usually 3 (occasionally 4 or 5), in a single whorl subtending the flower, sessile to subsessile, ovate to deltoid-obovate, 5-20 cm long and nearly as wide, acute or acuminate, not mottled, margins entire.

Flowers: perfect, solitary, terminal, pedicle 1-8 cm long; petals 3 (occasionally 4 or 5), ovate, white or pinkish, turning dark pink to dark red with age, longer than the sepals, up to 3 cm wide; sepals 3, green, narrowly oblong to oblong-elliptic, 1.5- 6 cm long and 2-15 mm wide; stamens 6.

Flower color: white, aging to pink

Bloom: April & May on the Palouse, into June at higher elevations

Bloom starts on: late April

Bloom ends on: late May

Fruit: fleshy, semi-dehiscent capsule, yellowish, broadly ovoid; seeds many, ovoid, large, shed in a sticky mass.

Characteristics:
Reproduces sexually by seed.
Perennating organ is a thickened rhizome. Offsets may sometimes be produced when a rhizome is wounded, but the plants are otherwise not clonal.
n=5 (Hitchcock et al 1969, Flora of North America Editorial Committee 1993, Baldwin et al 2004).
Diploids only are reported.
Pollinated by sap beetles, rove beetles, flower long-horned beetles, bumblebees, and honey bees (Jules 1998, Jules & Rathcke 1999). Since the flowers do not produce nectar, pollinators forage for pollen (Jules & Rathcke 1999). Geometrid moths probably pollinate the flowers are night (ibid).
Flowers are perfect.
Fruit is a fleshy, berry-like capsule.
Native peoples had medicinal uses for the plants.
Plants can be eaten cooked (Craighead et al 1963).
The rhizomes, as well as the fruits and seeds, are reportedly poisonous (Flora of North America Editorial Committee 1993).
Flowers are self incompatible (Jules 1998, Jules & Rathcke 1999).
Trillium seeds are myrmecochorous. They have an elaiosome which is attractive to ants. Ants carry the elaiosome and attached seed back to their nest, where they remove or eat the elaiosome and discard the seed.
Yellow jackets are also attracted to the elaiosome and disperse the seeds (Jules 1996, Jules 1998, Jules & Rathcke 1999).
Rodents eat the seeds (Mesler & Lu 1983, Jules 1998) and rhizomes. Deer eat the flowers.

Comments: Fragmentation of habitat has a negative effect on populations of T. ovatum. Populations within 65 meters of clearcuts have low seed recruitment (Jules 1998). The poor recruitment is due mostly to low numbers of pollinators and higher seed predation by rodents (Jules & Rathcke 1999).

Sun requirement: partial sun to full shade

Soil moisture: mesic

Sowing time: fall

Transplant time: fall or early spring

Stratification: cold moist

Seed yield: low

Seed harvest: difficult

Seed cleaning: difficult

Planting duration: no information available

Seed insect problem: rodents may eat the seeds

Seed shatter: low

Seed size: large

Seed harvest date: no information available

Herbaria: Specimen data and digital resources from The Consortium of Pacific Northwest Herbaria

Keywords: native upland perennial forb

Propagation:
Grows easily from seed (Hitchcock et al 1969).
Grow from seed. Can be carefully divided. Do not transplant from the wild (Kruckeberg 1993).
Collect seeds when capsules begin to split and sow immediately, uncovered. Keep pots in 80% shade. Germination usually occurs the following spring but may take 5-7 years to reach the flowering stage (Klest 2002).
Reproduces sexually by seed.

Notes: Trillium ovatum has large white flowers which turn pink with age. They are low growing plants which bloom in late April. Seeds of Trilliums are sometimes for sale in garden stores. They apparently require 6-7 years to flower from seed. Some specialty nurseries sell plants. They need moist shade and are usually a forest species. Common names include western trillium, wake-robin, white trillium, birthroot (Skinner et al 2005).

References:
Baldwin, B.G., S. Boyd, B.J. Ertter, D.J. Keil, R.W. Patterson, T.J. Rosatti, and D.H. Wilken (eds). 2004. Jepson Online Interchange for California Floristics. University and Jepson Herbaria, University of California, Berkeley, CA. Accessed 11/20/09 online at http://ucjeps.berkeley.edu/interchange.html

Craighead, John J., Frank C. Craighead, and Ray J. Davis. 1963. A Field Guide to Rocky Mountain Wildflowers. Houghton Mifflin Co. Boston, MA.

Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 7+ vols. New York and Oxford. Oxford University Press. Online at http://www.fna.org/FNA/

Hitchcock, C. Leo, Arthur Cronquist, Marion Ownbey, and J.W. Thompson. 1969. Vascular Plants of the Pacific Northwest. University of Washington Press. Seattle, WA. 5 vol.

Jules, Erik S. 1996. Yellow Jackets (Vespula vulgaris) as a Second Seed Disperser for the Myrmecochorous Plant, Trillium ovatum. American Midland Naturalist 135:367-369.

Jules, Erik S. 1998. Habitat Fragmentation and Demographic Change for a Common Plant: Trillium ovatum in Old-Growth Forest. Ecology 79:1645-1656.

Jules, Erik S., and Beverly J. Rathcke. 1999. Mechanisms of Reduced Trillium Recruitment along Edges of Old Growth Forest Fragments. Conservation Biology 13:784-793.

Klest, Sheila M. 2002. Propagation Protocol for Western Trilliums. Native Plants Journal 3(1):22-23.

Kruckeberg, Arthur R. 1996. Gardening with Native Plants of the Pacific Northwest. University of Washington Press. Seattle, WA.

Mesler, Michael R., and Karen L. Lu. 1983. Seed Dispersal of Trillium ovatum (Liliaceae) in Second-Growth Redwood Forests. American Journal of Botany 70:1460-1467.

Skinner, David M., Paul Warnick, Bill French, and Mary Fauci. 2005. More Palouse Forbs for Landscaping. USDA NRCS Pullman Plant Materials Center and Palouse Prairie Foundation. Online at http://www.wsu.edu/pmc_nrcs/Docs/More_Forbs_for_Landscaping.pdf

Links:
Plant Profile from the USDA PLANTS Database
Species description from Flora of North America
Species information from the University of Washington Herbarium