Trillium

Plants of this genus are perennial herbs growing from rhizomes. There are three large leaf-like bracts arranged in a whorl about a scape that rises directly from the rhizome. There are no true aboveground leaves but sometimes there are scale-like leaves on the underground rhizome. The bracts are photosynthetic and are sometimes called leaves. The inflorescence is a single flower with three green or reddish sepals and three petals in shades of red, purple, pink, white, yellow, or green. At the center of the flower there are six stamens and three stigmas borne on a very short style, if any. The fruit is fleshy and capsule-like or berrylike. The seeds have large, oily elaiosomes.[3][4]

Occasionally individuals have four-fold symmetry, with four bracts (leaves), four sepals, and four petals in the blossom.[7]

In 1753, Swedish botanist Carl Linnaeus established the genus Trillium by recognizing three species, T. cernuum, T. erectum, and T. sessile.[8] The type specimen T. cernuum described by Linnaeus was actually T. catesbaei,[9] an oversight that subsequently led to much confusion regarding the type species of this genus.

Initially the Trillium genus was placed in the family Liliaceae, which by 1981 had grown to about 280 genera and 4,000 species.[10] As part of an effort to deconstruct the polyphyletic family Liliaceae, many botanists considered Trillium and related genera to constitute a separate family Trilliaceae while others defined family Melanthiaceae for a similar purpose. In 1998, the Angiosperm Phylogeny Group assigned the genus Trillium, along with genera Paris and Pseudotrillium, to the family Melanthiaceae.[11]

The Trillium genus has traditionally been divided into two subgenera, T. subg. Trillium and T. subg. Sessilium, based on whether the flowers are pedicellate or sessile (resp.). The former is considered the more primitive group of species.[12][13][3] Until recently the sessile-flowered subgenus was known by the name Phyllantherum, but the name Sessilium has precedence and should be used.[14] T. subg. Sessilium has been shown to be a monophyletic group by molecular systematics but its segregation renders the remaining T. subg. Trillium paraphyletic.[15]

All names used in this section are taken from the International Plant Names Index.[16] Unless otherwise noted, the name has been accepted by World Checklist of Selected Plant Families.[17] The geographical locations are taken from the Flora of North America[3] except where noted.

Trillium species are native to North America and Asia.[3][4][50]

A fully general dichotomous key requires a mature, flowering plant.[3][51][52][53] The first step is to determine whether or not the flower sits on a pedicel, which determines the subgenus. (Any mature plant may be identified to this extent, even if it is not in bloom.) Identification proceeds based on flower parts, leaves, and other characteristics. A combination of characteristics is usually required to identify the plant.

Identification of a non-flowering, non-fruiting plant with bare leaves may be difficult. Although some species of Trillium have petioles (leaf stalks) and/or distinctive leaf shapes, these features are seldom sufficient to identify the plant down to the species level.

In eastern North America, jack-in-the-pulpit (Arisaema triphyllum) is often mistaken for bare-leaved Trillium. Both species are about the same height with trifoliate leaves but the former lacks 3-way rotational symmetry and has leaf veins unlike those of Trillium.

Trilliums are myrmecochorous, with ants as agents of seed dispersal. Ants are attracted to the elaiosomes on the seeds and collect them and transport them away from the parent plant. The seeds of Trillium camschatcense and T. tschonoskii, for example, are collected by the ants Aphaenogaster smythiesi and Myrmica ruginodis. Sometimes beetles interfere with the dispersal process by eating the elaiosomes off the seeds, making them less attractive to ants.[54] Vespicochory, seed dispersal by Vespula species (yellow jacket hornets), has also been observed for trilliums. The insects carry off the seeds and feed on the elaiosomes.[55]

Trillium grandiflorum (great white trillium)

Picking parts off a trillium plant can kill it even if the rhizome is left undisturbed.[56] Some species of trillium are listed as threatened or endangered and collecting these species may be illegal. Laws in some jurisdictions may restrict the commercial exploitation of trilliums and prohibit collection without the landowner's permission. In the US states of Michigan[56] and Minnesota[57] it is illegal to pick trilliums. In New York it is illegal to pick the red trillium.[58]

In 2009, a Private Members Bill was proposed in the Ontario legislature that would have made it illegal to in any way injure the common Trillium grandiflorum (white trillium) in the province (with some exceptions), however the bill was never passed.[59] The rare Trillium flexipes (drooping trillium) is also protected by law in Ontario, because of its decreasing Canadian population.[60]

High white-tailed deer population density has been shown to decrease or eliminate trillium in an area, particularly white trillium.[61]

Some species are harvested from the wild to an unsustainable degree. This is particularly dire in the case of T. govanianum, whose high selling-price as a folk medicine has motivated harvesters to destroy swathes of ecologically sensitive Himalayan forests, causing mudslides.[62]

Several species contain sapogenins. They have been used traditionally as uterine stimulants, the inspiration for the common name birthwort. In a 1918 publication, Joseph E. Meyer called it "beth root", probably a corruption of "birthroot". He claimed that an astringent tonic derived from the root was useful in controlling bleeding and diarrhea.[63]

The white trillium (Trillium grandiflorum) serves as the official flower and emblem of the Canadian province of Ontario. It is an official symbol of the Government of Ontario. The large white trillium is the official wildflower of Ohio.[64] In light of their shared connection to the flower, the Major League Soccer teams in Toronto and Columbus compete with each other for the Trillium Cup.

Citizen scientists regularly report observations of Trillium species from around the world. T. grandiflorum, T. erectum, and T. ovatum (in that order) are the most often observed Trillium species.[65]

Trillium is the literary magazine of Ramapo College of New Jersey, which features poetry, fiction, photography, and other visual arts created by Ramapo students.[66]

In Mexican LGBT culture, the trillium is included as a symbol on their version of the bisexual pride flag.[67]

• 
  Nodding trillium (Trillium cernuum)
• 
  Idaho trillium (Trillium petiolatum)
• 
  White trillium (Trillium grandiflorum)
• 
  Red trillium (Trillium erectum)
• 
  Pacific trillium (Trillium ovatum)
• 
  Prairie trillium (Trillium recurvatum)
• 
  Relict trillium (Trillium reliquum) an endangered species
• 
  Painted trillium (Trillium undulatum)

• Barksdale, Lane (1938). "The pedicellate species of Trillium found in the southern Appalachians". Journal of the Elisha Mitchell Scientific Society. 54 (2): 271–296. JSTOR 24332541.
• Case, Frederick W.; Case, Roberta B. (1997). Trilliums. Portland, Oregon: Timber Press. ISBN 978-0-88192-374-2.
• Freeman, J. D. (1975). "Revision of Trillium subgenus Phyllantherum (Liliaceae)". Brittonia. 27 (1): 1–62. doi:10.2307/2805646. JSTOR 2805646. S2CID 20824379.

Wikimedia Commons has media related to Trillium.

• Interactive Identification Key (Java)
• Utah Agricultural Experiment Station — Fact Sheets
• McKelvie, D. Woodland Plants: The Trillium. Ontario Woodlot Association.
• Biodiversity Information Serving Our Nation (BISON) occurrence data and maps for Trillium