Trillium (trillium, wakerobin, toadshade, tri flower, birthroot, birthwort, and sometimes "wood lily") is a genus of about fifty flowering plant species in the family Melanthiaceae. Trillium species are native to temperate regions of North America and Asia,[3][4] with the greatest diversity of species found in the southern Appalachian Mountains in the southeastern United States.[5][6]

Description

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][better source needed]

Taxonomy

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. In the nineteenth and early twentieth centuries it was sometimes placed in a smaller family, Trilliaceae.[10] By 1981 Liliaceae had grown to about 280 genera and 4,000 species.[11] As it became clearer that the very large version of Liliaceae was polyphyletic, some botanists preferred to place Trillium and related genera into that separate family. Others defined a larger family, Melanthiaceae, for a similar purpose, but included several other genera not historically recognized as close relatives of Trillium. This latter approach was followed in 1998 by the Angiosperm Phylogeny Group, which assigned the genus Trillium, along with its closest relatives, Paris and Pseudotrillium, to the family Melanthiaceae.[12] However, other taxonomists have since preferred to break up the heterogenous Melanthiaceae into several smaller monophyletic families, each with more coherent morphological features, returning Trillium to a resurrected Trilliaceae.[13]

In 1850, German botanist Carl Sigismund Kunth segregated Trillium govanianum into genus Trillidium.[14] A proposal to segregate Trillium undulatum into genus Trillidium Kunth was put forward in 2018.[15] Some authorities accept Trillidium Knuth while others consider it to be a synonym for Trillium L.[13][16]

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 with respect to their attachment to the apex of the scape. The former is considered the more primitive group.[17][18][3] Until recently the sessile-flowered subgenus was known by the name Phyllantherum, but the name Sessilium has precedence and should be used instead.[19] T. subg. Sessilium has been shown to be a monophyletic group by molecular systematics but its segregation renders the remaining T. subg. Trillium paraphyletic.[20]

All names used in this section are taken from the International Plant Names Index.[21] As of December 2021, Plants of the World Online (POWO) accepts 49 species and 5 named hybrids,[2] all of which are listed below. The geographical locations are taken from POWO and the Flora of North America,[3] except where noted.

North American taxa

The following species belong to T. subg. Trillium, that is, they bear pedicellate flowers (on a short stalk) but lack mottled leaves.[22]

  • Trillium catesbaei Elliott – Alabama, Georgia, North Carolina, South Carolina, Tennessee
  • Trillium cernuum L. – Manitoba, New Brunswick, Newfoundland, Nova Scotia, Ontario, Prince Edward Island, Quebec, Saskatchewan; Connecticut, Delaware, District of Columbia, Illinois, Indiana, Iowa, Maine, Maryland, Massachusetts, Michigan, Minnesota, New Hampshire, New Jersey, New York, North Dakota, Ohio, Pennsylvania, Rhode Island, South Dakota, Vermont, Virginia, West Virginia, Wisconsin; Saint Pierre and Miquelon
  • Trillium crassifolium Piper – Washington
  • Trillium × crockerianum Halda – California
  • Trillium erectum L. – New Brunswick, Nova Scotia, Ontario, Quebec; Connecticut, Delaware, Georgia, Illinois, Indiana, Kentucky, Maine, Maryland, Massachusetts, Michigan, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Vermont, Virginia, West Virginia
  • Trillium flexipes Raf. – Ontario; Alabama, Arkansas,[6] Delaware, Illinois, Indiana, Iowa, Kentucky, Maryland,[6] Michigan, Minnesota, Missouri, New York, Ohio, Pennsylvania, South Dakota, Tennessee, Virginia, West Virginia, Wisconsin
  • Trillium georgianum S.B.Farmer – Georgia
  • Trillium grandiflorum (Michx.) Salisb. – Nova Scotia, Ontario, Quebec; Alabama, Connecticut, Delaware, Georgia, Illinois, Indiana, Iowa, Kentucky, Maine, Maryland, Massachusetts, Michigan, Minnesota, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, South Carolina, Tennessee, Vermont, Virginia, West Virginia, Wisconsin
  • Trillium hibbersonii (T.M.C.Taylor & Szczaw.) D.O'Neill & S.B.Farmer – British Columbia
  • Trillium nivale Riddell – Illinois, Indiana, Iowa, Kentucky, Maryland, Michigan, Minnesota, Missouri, Nebraska, Ohio, Pennsylvania, South Dakota, West Virginia, Wisconsin
  • Trillium ovatum Pursh – Alberta, British Columbia; California, Colorado, Idaho, Montana, Oregon, Washington, Wyoming
  • Trillium persistens W.H.Duncan – Georgia, South Carolina
  • Trillium pusillum Michx. – Alabama, Arkansas, Georgia,[6] Kentucky, Louisiana, Maryland, Mississippi, Missouri, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia, West Virginia
  • Trillium rugelii Rendle – Alabama, Georgia, North Carolina, South Carolina, Tennessee
  • Trillium scouleri Rydb. ex Gleason – Alberta, British Columbia; Colorado, Idaho, Montana, Washington, Wyoming
  • Trillium simile Gleason – Georgia, North Carolina, Tennessee
  • Trillium sulcatum T.S.Patrick – Alabama, Georgia, Kentucky, North Carolina, Tennessee, Virginia, West Virginia
  • Trillium undulatum Willd. – New Brunswick, Nova Scotia, Ontario, Prince Edward Island, Quebec; Connecticut, Georgia, Kentucky, Maine, Maryland, Massachusetts, Michigan, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Vermont, Virginia, West Virginia
  • Trillium vaseyi Harb. – Alabama, Georgia, North Carolina, South Carolina, Tennessee

The following species belong to T. subg. Sessilium, that is, they bear sessile flowers (with no stalk) and have mottled leaves.[23]

Asian taxa

All of the following species belong to T. subg. Trillium, that is, they bear pedicellate flowers.[20]

Other taxa

  • Trillium texanum Buckley, also known as Trillium pusillum var. texanum (Buckley) Reveal & C.R.Broome, are considered by some authorities to be synonyms for Trillium pusillum var. pusillum.[43]
  • Trillium tennesseense E. E. Schill & Floden is considered by some authorities to be a synonym for Trillium lancifolium Raf.[44]
  • Trillium parviflorum V.G.Soukup is an accepted name by some authorities[45][46] while others regard this name as a synonym of T. albidum subsp. parviflorum (V.G.Soukup) K.L.Chambers & S.C.Meyers.[47][48]
  • Trillium rivale S.Watson[49] has been segregated to a monotypic genus as Pseudotrillium rivale (S.Watson) S.B.Farmer.[50]

Distribution

Trillium species are native to North America and Asia.[3][4][51]

North America

More than three dozen Trillium species are found in North America,[3] most of which are native to eastern North America. Just six species are native to western North America: T. albidum, T. angustipetalum, T. chloropetalum, T. kurabayashii, T. ovatum, and T. petiolatum. Of these, only T. ovatum is pedicellate-flowered.

Canada

Trillium species are found across Canada, from Newfoundland to southern British Columbia. The greatest diversity of species are found in Ontario, Quebec, and Nova Scotia.[3]

United States

Except for the desert regions of the southwestern United States, Trillium species are found throughout the contiguous U.S. states. In the western United States, species are found from Washington to central California, east to the Rocky Mountains. In the eastern United States, species range from Maine to northern Florida, west to the Mississippi River valley. Trillium species are especially diverse in the southeastern United States, in Georgia, Tennessee, Alabama, North Carolina, and South Carolina.[3] The state of Georgia is home to 21 species of trillium.

  • Alabama: T. catesbaei, T. cuneatum, T. decipiens, T. decumbens, T. flexipes, T. grandiflorum, T. lancifolium, T. maculatum, T. pusillum, T. recurvatum, T. rugelii, T. sessile, T. stamineum, T. sulcatum, T. underwoodii, T. vaseyi
  • Alaska: none
  • Arizona: none
  • Arkansas: T. flexipes, T. pusillum, T. recurvatum, T. sessile, T. viridescens
  • California: T. albidum, T. angustipetalum, T. chloropetalum, T. × crockerianum, T. kurabayashii, T. ovatum
  • Colorado: T. ovatum, T. scouleri
  • Connecticut: T. cernuum, T. erectum, T. grandiflorum, T. undulatum
  • Delaware: T. cernuum, T. erectum, T. flexipes, T. grandiflorum
  • District of Columbia: T. cernuum
  • Florida: T. decipiens, T. lancifolium, T. maculatum, T. underwoodii
  • Georgia: T. catesbaei, T. cuneatum, T. decipiens, T. decumbens, T. delicatum, T. discolor, T. erectum, T. georgianum, T. grandiflorum, T. lancifolium, T. luteum, T. maculatum, T. persistens, T. pusillum, T. reliquum, T. rugelii, T. simile, T. sulcatum, T. underwoodii, T. undulatum, T. vaseyi
  • Hawaii: none
  • Idaho: T. ovatum, T. petiolatum, T. scouleri
  • Illinois: T. cernuum, T. erectum, T. flexipes, T. grandiflorum, T. nivale, T. recurvatum, T. sessile, T. viride
  • Indiana: T. cernuum, T. erectum, T. flexipes, T. grandiflorum, T. nivale, T. recurvatum, T. sessile
  • Iowa: T. cernuum, T. flexipes, T. grandiflorum, T. nivale, T. recurvatum
  • Kansas: T. sessile, T. viridescens
  • Kentucky: T. cuneatum, T. erectum, T. flexipes, T. grandiflorum, T. luteum, T. nivale, T. pusillum, T. recurvatum, T. sessile, T. sulcatum, T. undulatum
  • Louisiana: T. foetidissimum, T. gracile, T. ludovicianum, T. pusillum (syn: T. texanum), T. recurvatum
  • Maine: T. cernuum, T. erectum, T. grandiflorum, T. undulatum
  • Maryland: T. cernuum, T. erectum, T. flexipes, T. grandiflorum, T. nivale, T. pusillum, T. sessile, T. undulatum
  • Massachusetts: T. cernuum, T. erectum, T. grandiflorum, T. undulatum
  • Michigan: T. cernuum, T. erectum, T. flexipes, T. grandiflorum, T. nivale, T. recurvatum, T. sessile, T. undulatum
  • Minnesota: T. cernuum, T. flexipes, T. grandiflorum, T. nivale
  • Mississippi: T. cuneatum, T. foetidissimum, T. ludovicianum, T. pusillum, T. recurvatum, T. stamineum
  • Missouri: T. flexipes, T. nivale, T. pusillum, T. recurvatum, T. sessile, T. viride, T. viridescens
  • Montana: T. ovatum, T. scouleri
  • Nebraska: T. nivale
  • Nevada: none
  • New Hampshire: T. cernuum, T. erectum, T. grandiflorum, T. undulatum
  • New Jersey: T. cernuum, T. erectum, T. grandiflorum, T. undulatum
  • New Mexico: none
  • New York: T. cernuum, T. erectum, T. flexipes, T. grandiflorum, T. sessile, T. undulatum
  • North Carolina: T. catesbaei, T. cuneatum, T. discolor, T. erectum, T. grandiflorum, T. luteum, T. pusillum, T. rugelii, T. sessile, T. simile, T. sulcatum, T. undulatum, T. vaseyi
  • North Dakota: T. cernuum
  • Ohio: T. cernuum, T. erectum, T. flexipes, T. grandiflorum, T. nivale, T. recurvatum, T. sessile, T. undulatum
  • Oklahoma: T. pusillum, T. sessile, T. viridescens
  • Oregon: T. albidum, T. kurabayashii, T. ovatum, T. petiolatum
  • Pennsylvania: T. cernuum, T. erectum, T. flexipes, T. grandiflorum, T. nivale, T. sessile, T. undulatum
  • Rhode Island: T. cernuum, T. erectum, T. undulatum
  • South Carolina: T. catesbaei, T. cuneatum, T. discolor, T. erectum, T. grandiflorum, T. lancifolium, T. maculatum, T. persistens, T. pusillum, T. reliquum, T. rugelii, T. undulatum, T. vaseyi
  • South Dakota: T. cernuum, T. flexipes, T. nivale
  • Tennessee: T. catesbaei, T. cuneatum, T. decumbens, T. erectum, T. flexipes, T. grandiflorum, T. lancifolium, T. luteum, T. pusillum, T. recurvatum, T. rugelii, T. sessile, T. simile, T. stamineum, T. sulcatum, T. tennesseense, T. undulatum, T. vaseyi
  • Texas: T. gracile, T. ludovicianum, T. pusillum (syn: T. texanum), T. recurvatum, T. viridescens
  • Utah: none
  • Vermont: T. cernuum, T. erectum, T. grandiflorum, T. undulatum
  • Virginia: T. cernuum, T. erectum, T. flexipes, T. grandiflorum, T. pusillum, T. sessile, T. sulcatum, T. undulatum
  • Washington: T. albidum, T. ovatum, T. petiolatum, T. scouleri
  • West Virginia: T. cernuum, T. erectum, T. flexipes, T. grandiflorum, T. nivale, T. pusillum, T. sessile, T. sulcatum, T. undulatum
  • Wisconsin: T. cernuum, T. flexipes, T. grandiflorum, T. nivale, T. recurvatum
  • Wyoming: T. ovatum, T. scouleri

Other

Asia

In Asia, the range of Trillium species extends from the Himalayas across China, Korea, Japan, and eastern Russia to the Kuril Islands. The greatest diversity of Trillium species is found on the islands of Japan and Sakhalin.

Identification

A fully general dichotomous key requires a mature, flowering plant.[3][52][53][54] 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.

Ecology

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.[55] 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.[56]

Hybrids

As of December 2021, Plants of the World Online recognizes five named hybrids, four in Asia and one in North America:[2]

  • Trillium × crockerianum (Trillium ovatum × Pseudotrillium rivale)
  • Trillium × hagae (Trillium camschatcense × Trillium tschonoskii)
  • Trillium × komarovii (Trillium camschatcense x unknown)
  • Trillium × miyabeanum (Trillium apetalon × Trillium tschonoskii)
  • Trillium × yezoense (Trillium apetalon × Trillium camschatcense)

Three of the Asian hybrids, T. × hagae, T. × miyabeanum, and T. × yezoense, are well studied,[57] but little is known about the Asian hybrid T. × komarovii. Based on its synonyms,[58] one of its parents may be T. camschatcense.

The only named hybrid in North America is T. × crockerianum. As originally described, its parents are Trillium ovatum and Trillium rivale,[59] but the latter species is now a member of genus Pseudotrillium, and so T. × crockerianum has become an intergeneric hybrid.

In 1982, Haga and Channell crossed the Asiatic species Trillium camschatcense with several North American species. Of those, the crosses with T. erectum, T. flexipes, and T. vaseyi produced solid, seemingly viable seed. Seeds of the cross between T. camschatcense and T. erectum flowered in 9 to 10 years.[60]

Disease

Diseased T. grandiflorum with virescent petals, extra petals, and other abnormalities

Various Trillium species are susceptible to a greening disorder caused by bacterial organisms called phytoplasmas that alter the morphology of infected plants.[61] Symptoms of phytoplasma infection include abnormal green markings on the petals (floral virescence), extra leaves (phyllody), and other abnormal characteristics.[62] Infected populations occur throughout the species range but are prevalent in Ontario, Michigan, and New York.[63]

For many years, this condition was thought to originate from mutation, and so many of these forms were given taxonomic names now known to be invalid. In 1971, Hooper, Case, and Meyers used electron microscopy to detect the presence of mycoplasma-like organisms (i.e., phytoplasmas) in T. grandiflorum with virescent petals. The means of transmission was not established but leafhoppers were suspected.[64] As of November 2021, the insect vector for Trillium greening disorder is unknown.

Phytoplasmas were positively identified in T. grandiflorum and T. erectum in Ontario in 2016. Phylogenetic analysis supported the grouping of the phytoplasmas isolated from infected plants as a related strain of 'Candidatus Phytoplasma pruni' (subgroup 16SrIII-F) with 99% sequence identity.[65][66] This subgroup of phytoplasmas is associated with various other diseases, including milkweed yellows, Vaccinium witches' broom, and potato purple top.[67]

Conservation

Trillium grandiflorum (great white trillium)

Picking parts off a trillium plant can kill it even if the rhizome is left undisturbed.[68] 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[68] and Minnesota[69] it is illegal to pick trilliums. In New York it is illegal to pick the red trillium.[70]

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.[71] The rare Trillium flexipes (drooping trillium) is also protected by law in Ontario, because of its decreasing Canadian population.[72]

High white-tailed deer population density has been shown to decrease or eliminate trillium in an area, particularly white trillium.[73]

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.[74]

Medicinal uses

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.[75]

Culture

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.[76] 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.[77]

Trillium is the literary magazine of Ramapo College of New Jersey, which features poetry, fiction, photography, and other visual arts created by Ramapo students.[78]

In Mexican LGBT culture, the trillium is included as a symbol on their version of the bisexual pride flag.[79][irrelevant citation]

Gallery

Bibliography

References

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