Giant Trillium

Giant Trillium © EKennedy

Common Trillium, Giant Wakerobin
Trillium chloropetalum

Description (Jepson,

  • Monocotyledon
    • Monocots are a major lineage of flowering plants; see family for general characteristics
  • False-hellebore Family (Melanthiaceae)
  • Perennial herb
    • Grows from rhizomes (horizontal underground stems)
  • Leaves
    • Single whorl of 3 leaves, directly attached to the stem (sessile)
    • Large (up to 6 in.) and triangular
    • Dark green, often with brown to purple mottling
    • Venation is netted, unusual for a monocot
  • Flowers
    • One large flower per stem, directly attached to the center of the leaves (sessile)
    • Dark purple to white, with flower parts in threes
      • 3 sepals (usually green, outer flower parts), to 3 in. long
      • 3 erect petals, to 4 in. long
      • Partly-concealed purple stamens (male flower parts) and purple ovary (characteristic of this species)
    • Ovary superior (above the attachment of other flower parts)
  • Fruit is a 6-angled, purple, berry-like capsule (a dry, multi-chambered fruit that splits open at maturity)
  • Height to 28 in.
Flower © DSchiel


  • Native to California
    • Grows in woodlands, chaparral, generally on moist slopes and canyon banks in alluvial soils (eJepson)
    • See Calflora for statewide observations of this plant
  • Grows at elevations between 300 and 6,500 ft.

Uses (San Mateo County Parks prohibits removal of any natural material)

  • Native people made a heated poultice for chest pains and a poultice of rhizome scrapings to treat burns
  • CAUTION – Trillium fruit and roots contain saponins, which if eaten in large quantities, can cause gastrointestinal distress (Sanders 2020)

Name Derivation

  • Trillium (TRIL-ee-um) – Latin for “three,” referring to plant parts in sets of threes
  • chloropetalum (klor-o-PET-a-lum) – from the Greek chloros, “green” and pétalo, “petal,” as the petals are occasionally green


  • Geophytes, e.g. plants growing from bulbs, corms, and rhizomes, are adapted to survive fire, our Mediterranean climate’s long, dry summers, and extended droughts
    • Above-ground growth dies back after flowering, while underground the plant survives with stored water and nutrients
  • Seeds of Trillium require 2 springs to break dormancy, with roots emerging in the first spring and leaves in the second
    • Giant trillium may take 5 years of growth before flowering (Lady Bird Johnson 2014)
  • Flower odor generally sweet, rose-like, or slightly spicy
  • Trilliums use a strategy called myrmecochory for seed dispersal (NatureServe 2020)
    • White, fleshy appendage on the seed tip is a nutrient-rich food packet, an elaiosome, that attracts ants
    • Ants carry seeds to their colony up to 1 mile away, feed the packet to their larvae, and discard the seeds, effectively planting them
    • This strategy is an example of mutualism as it benefits both species
    • Miner’s lettuce (Claytonia perfoliata ssp. perfoliata) is another Edgewood species that uses myrmecochory
  • Mammals, like deer, ingest and defecate Trillium seeds, providing another means of dispersal (NatureServe. 2020)
  • Trilliums can be divided into 2 major groups (Collett 2005)
    • Sessile (toad shadows) – species lacking a pedicel (stalk of a single flower), including giant trillium
    • Pedicellate (wakerobins) – species with a pedicel, including Western trillium (Trillium ovatum ssp. ovatum), common in the Santa Cruz mountains
  • Trilliums actually have no true leaves or stems above ground (Pistrang)
    • The “stem” is technically a part of the rhizome
    • Although some sources, including Jepson, refer to “leaves,” they are technically bracts located just below (subtending) the flower

ID Tips

  • Can’t miss this plant! Three large green leaves with mottling and 3 large erect petals, surrounded by 3 prominent sepals, make this one an eye-catcher

At Edgewood

  • Found in moist, shady areas of woodlands
  • Flowers February – April

See General References

Specific References

Collett, R. 2005, Jan. Toadshades of the Santa Cruz Mountains. Pacific Horticultural Society.

Lady Bird Johnson Wildflower Center. 2014. Trillium chloropetalum. Native Plants of North America. University of Texas at Austin.

NatureServe. 2020. Trillium chloropetalum. NatureServe Explorer.

Pistrang, M. Plant of the Week: Catesby’s Trillium (Trillium catesbaei). US Forest Service, USDA.

Sanders, A. 2020. Garden Guides: Is Trillium Poisonous?