Trillium (trillium,wakerobin,toadshade,tri flower,birthroot,birthwort, and sometimes"wood lily") is agenus of about fiftyflowering plantspecies in the familyMelanthiaceae.Trillium species are native to temperate regions of North America and Asia,[3][4] with the greatest diversity of species found in the southernAppalachian Mountains in the southeastern United States.[5][6]
Plants of this genus areperennialherbs growing fromrhizomes. There are three large leaf-likebracts arranged in a whorl about ascape 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 arephotosynthetic and are sometimes called leaves. Theinflorescence is a single flower with three green or reddishsepals and threepetals in shades of red, purple, pink, white, yellow, or green. At the center of the flower there are sixstamens and threestigmas borne on a very short style, if any. The fruit is fleshy and capsule-like or berrylike. The seeds have large, oilyelaiosomes.[3][4]
Occasionally individuals have four-fold symmetry, with four bracts (leaves), four sepals, and four petals in the blossom.[7][better source needed]. Thetetramerous condition has been described for several species ofTrillium includingT. chloropetalum,T. erectum,T. grandiflorum,T. maculatum,T. sessile, andT. undulatum.[8]
In 1753, Swedish botanistCarl Linnaeus established the genusTrillium by recognizing three species,Trillium cernuum,Trillium erectum, andTrillium sessile.[9] Thetype specimenTrillium cernuum described by Linnaeus was actuallyTrillium catesbaei,[10] an oversight that subsequently led to much confusion regarding the type species of this genus.
Initially theTrillium genus was placed in the familyLiliaceae. In the nineteenth and early twentieth centuries it was sometimes placed in a smaller family,Trilliaceae.[11] By 1981Liliaceae had grown to about 280 genera and 4,000 species.[12] As it became clearer that the very large version of Liliaceae waspolyphyletic, some botanists preferred to placeTrillium 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 ofTrillium. This latter approach was followed in 1998 by theAngiosperm Phylogeny Group, which assigned the genusTrillium, along with its close relativeParis, to the family Melanthiaceae.[13] However, other taxonomists have since preferred to break up the heterogenous Melanthiaceae into several smaller monophyletic families, each with more coherent morphological features, returningTrillium to a resurrected Trilliaceae.[14]
In 1850, German botanistCarl Sigismund KunthsegregatedTrillium govanianumWall. ex D.Don into genusTrillidium.[15] Some authorities considerTrillidiumKunth to be a synonym forTrilliumL.,[16] while others recognize the taxonTrillidium govanianum(Wall. ex D.Don) Kunth based on morphological differences (with otherTrillium species) and molecular evidence.[17][18] Still others support the segregation ofTrillium undulatumWilld. into genusTrillidium alongsideTrillidium govanianum.[14][19]
TheTrillium genus has traditionally been divided into twosubgenera,Trillium subgenusTrillium andTrillium subgenusPhyllantherum, based on whether the flower ispedicellate orsessile.[21][22] At the time, the former subgenus was considered to be the more primitive group.[23][24][3] Based onmolecular systematics,Trillium subgen. Phyllantherum has been shown to be amonophyletic group, but its segregation renders the remainingTrillium subgen. Trilliumparaphyletic.[25]
Trillium subgenusPhyllantherum was named byConstantine Samuel Rafinesque in 1820,[26] but since he did not provide a description, the name was declared invalid in 2014.[27] At that time, the correct name was thought to beTrillium subgen. Sessilium,[28] which was described by Rafinesque in 1830. However, that name was later found to be incorrect as well.[29] As of July 2022[update], the correct name of the subgenus isTrilliumL. subgen. SessiliaRaf.[30] Itstype species isTrillium sessileL.
In 1819, Rafinesque described and named the genusDelostylis,[31] and then placedTrillium stylosumNutt. (now a synonym forTrillium catesbaeiElliott) into the new genus. Reversing himself a decade later, Rafinesque instead placedTrillium stylosum into a new subgenusDelostylium in 1830.[32] Presumably Rafinesque had intended the subgeneric name to replace the earlier generic name, and so the correct name of the former isTrilliumL. subgen. Delostylis(Raf.) Raf..[33][29] Its type species isTrillium catesbaei. Historically, the subgenus has been known as the Catesbaei group.[34][35] The wordDelostylis means "with a small but conspicuous style".[36]
Trillium rivale, first described in 1885, was segregated into genusPseudotrilliumS.B.Farmer in 2002.[18] The namePseudotrillium rivale(S.Watson) S.B.Farmer is widely recognized.
Trillium govanianum, first described in 1839, was segregated into genusTrillidiumKunth in 1850.[15] However, the nameTrillidium govanianum(Wall. ex D.Don) Kunth is not widely recognized.
Trillium undulatum, first described in 1801, was segregated into genusTrillidium in 2018,[19] but the nameTrillidium undulatum(Willd.) Floden & E.E.Schill. is controversial and not widely recognized.
Phylogenetic analysis placesTrillidium govanianum andTrillidium undulatum together in a clade with high support.[37] However, sinceTrillium andTrillidium are both individually and collectively monophyletic, it is a matter of choice whether or not to recognize genusTrillidium.
Excluding the segregate taxa listed above, the remaining taxa separate into four clades with the following names:[29]
Traditionally,Trillium subgen. Trillium has includedall pedicellate-flowered species (which is aparaphyletic group), but in 2022, the subgenus wascircumscribed as aclade of fourteen (14) species.[38] Its type species isTrillium erectumL. Historically, the subgenus has been known as the Erectum group.[34][39][40][35][41]
Trillium subgen. Callipetalon was described by Jayne A. Lampley and Edward E. Schilling in 2022.[42] The wordCallipetalon means "beautiful petal", a reference to "the famously beautiful flowers" of its type species,Trillium grandiflorum(Michx.) Salisb.[43] Historically, the subgenus has been known as the Grandiflorum group.[34][39][40][35][41]
This leads to a four-part concept ofTrillium that sharply contrasts with the traditional pedicellate vs. sessile dichotomy outlined previously.[44]
Trillium subgen. Trillium, theErectum group, is a group of pedicellate-flowered trilliums that includesTrillium erectum. The subgenus wascircumscribed as aclade of fourteen (14) species in 2022.[38] Species in this subgenus havepedicellate flowers (on a stalk) with three distinctstigmas (nostyle) and solid green leaves (not mottled). They are distributed across North America and Asia. Hybrids are common within this subgenus (the only group of pedicellate-flowered trilliums with natural hybrids).
Trillium camschatcenseKer Gawl.[48][49] – NE China (Jilin), Japan, Korea, Kuril Islands, E Russia (Primorsky Krai, Khabarovsk Krai, Kamchatka Peninsula, Sakhalin)
Trillium cernuumL. – Manitoba, New Brunswick, Newfoundland, Nova Scotia, Ontario, Prince Edward Island, Quebec, Saskatchewan; Connecticut, Delaware, 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 erectumL. – 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 flexipesRaf. – 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 ×hagaeMiyabe & Tatew.[52] (Trillium camschatcense ×Trillium tschonoskii) – Japan, E Russia (S Sakhalin)
Trillium hibbersonii(T.M.C.Taylor & Szczaw.) D.O'Neill & S.B.Farmer – British Columbia
Trillium ×komaroviiH.Nakai & Koji Ito[53] (Trillium camschatcense × unknown) – Japan, E Russia (Primorsky Krai)
Trillium subgen. Callipetalon, theGrandiflorum group, is a group of pedicellate-flowered trilliums that includesTrillium grandiflorum. The subgenus wascircumscribed as aclade of three (3) species in 2022.[43] Species in the subgenus havepedicellate flowers (on a stalk) and solid green leaves (exceptT. ovatum on the west coast of California, which occasionally has mottled leaves). Thestigmas are fused together at their bases (basallyconnate) but lack a definitestyle. They are distributed across North America (but not Asia). Flowers were and still are consumed and used byindigenous peoples in various regions of North America.
Trillium grandiflorum(Michx.) Salisb. – Nova Scotia, Ontario, Quebec; Alabama, Connecticut, Delaware, District of Columbia, 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 nivaleRiddell – Illinois, Indiana, Iowa, Kentucky, Maryland, Michigan, Minnesota, Missouri, Nebraska, Ohio, Pennsylvania, South Dakota, West Virginia, Wisconsin
Trillium subgen. Delostylis, theCatesbaei group, is a group of pedicellate-flowered trilliums that includesTrillium catesbaei. The subgenus wascircumscribed as aclade of seven (7) species in 2022.[61] Species in this subgenus havepedicellate flowers (except for one variety ofT. pusillum) with a definitestyle and solid green leaves (not mottled). Distribution is restricted to the southeastern and south central United States.
Trillium catesbaeiElliott – Alabama, Georgia, North Carolina, South Carolina, Tennessee
Trillium pusillumMichx. – Alabama, Arkansas, Kentucky, Maryland, Mississippi, Missouri, North Carolina, Oklahoma, South Carolina, Tennessee, Virginia, West Virginia
Trillium subgen. Sessilia, thesessile-flowered trilliums, is a group of species that includesTrillium sessile. The subgenus wascircumscribed as aclade of twenty-six (26) species in 2022.[62] Species in this subgenus havesessile flowers (no flower stalk), erect petals (except inT. stamineum), and mottled leaves (except inT. petiolatum and occasionally in plants of other sessile-flowered species).[22]
Trillium sessileL. – Alabama, Arkansas, District of Columbia, Illinois, Indiana, Kansas, Kentucky, Maryland, Michigan, Missouri, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, Tennessee, Virginia, West Virginia
The following pair of taxa do not fit into any of the above groups since they are markedly different from otherTrillium species. There is evidence to support the segregation of these species into a separate genus (Trillidium) but the proposal is controversial.
Trillium govanianumWall. ex D.Don[63][64][65] – NE Afghanistan, Bhutan, China (Tibet Autonomous Region, Yunnan), N + NE India (Himachal Pradesh, Jammu and Kashmir, Sikkim, Uttarakhand), Nepal, N Pakistan
Trillium undulatumWilld. – 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 parviflorumV.G.Soukup is an accepted name by some authorities[66] while others regard this name as a synonym ofT. albidum subsp.parviflorum(V.G.Soukup) K.L.Chambers & S.C.Meyers.[67]
Trillium × crockerianumHalda was originally described as a hybrid with parentsTrillium ovatum andTrillium rivale,[69] but since the latter is now a member of genusPseudotrillium, the hybrid has become an undescribedintergeneric hybrid, and therefore its taxonomic placement is uncertain.[70]
More than three dozenTrillium 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, andT. petiolatum. Of these, onlyT. ovatum is pedicellate-flowered.
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]
Except for the desert regions of the southwestern United States,Trillium species are found throughout thecontiguous U.S. states. In the western United States, species are found from Washington to central California, east to theRocky Mountains. In the eastern United States, species range from Maine to northern Florida, west to theMississippi 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.
In Asia, the range ofTrillium species extends from theHimalayas across China, Korea, Japan, and eastern Russia to the Kuril Islands. The greatest diversity ofTrillium species is found on the islands of Japan and Sakhalin.
A fully generaldichotomous key requires a mature, flowering plant.[3][74][75][76] The first step is to determine whether or not the flower sits on apedicel, 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 ofTrillium havepetioles (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-leavedTrillium. Both species are about the same height withtrifoliate leaves but the former lacks 3-way rotational symmetry and has leaf veins unlike those ofTrillium.
Trilliums aremyrmecochorous, that is,ants act as agents ofseed dispersal. Each seed of a ripe fruit has a white fleshy appendage called anelaiosome. Ants are attracted to the elaiosome, so much so they often bore holes into the fruit instead of waiting for it to drop off on its own.[77] The ants carry the seeds back to their nest where they eat the elaiosomes and discard the seeds. Here the seeds eventually germinate, an average of about 1 meter away from the parent plant.
Yellow jackets (Vespula spp.) and other wasps are similarly attracted to elaiosomes. The wasps carry off the seeds and feed on the elaiosomes an average of about 1.4 meters away from the parent plant. Yellow jackets are documented seed dispersers for at least three species ofTrillium (T. catesbaei,T. cuneatum,T. undulatum).[79]
The seeds of someTrillium species are more attractive to ants than others. Widely distributed species (e.g.,Trillium grandiflorum,Trillium catesbaei, andTrillium cuneatum) are more attractive to ants than narrowly endemic species (e.g.,Trillium lancifolium,Trillium discolor, andTrillium decumbens).[80]
As of February 2022[update],Plants of the World Online recognizes five named hybrids,[2] four in Asia and one in North America. Three of the Asian hybrids,T. ×hagae,T. ×miyabeanum, andT. ×yezoense, are well studied,[81] but little is known about the Asian hybridT. ×komarovii. One of its parents isT. camschatcense but the other parent is unknown.[53]
The only named hybrid in North America isT. ×crockerianum whosetype specimen was collected inDel Norte County, California.[69] As originally described, its parents areTrillium ovatum andTrillium rivale, but the latter species is now a member of genusPseudotrillium, and soT. ×crockerianum has become anintergeneric hybrid.
In 1982, Haga and Channell crossed the Asiatic speciesTrillium camschatcense with several North American species. Of those, the crosses withT. erectum,T. flexipes, andT. vaseyi produced solid, seemingly viable seed. Seeds of the cross betweenT. camschatcense andT. erectum flowered in 9 to 10 years.[82]
DiseasedT. grandiflorum with virescent petals, extra petals, and other abnormalities
VariousTrillium species are susceptible to a greening disorder caused by bacterial organisms calledphytoplasmas that alter the morphology of infected plants.[83] Symptoms of phytoplasma infection include abnormal green markings on the petals (floralvirescence), extra leaves (phyllody), and other abnormal characteristics.[84] Infected populations occur throughout the species range but are prevalent in Ontario, Michigan, and New York.[85]
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 usedelectron microscopy to detect the presence of mycoplasma-like organisms (i.e., phytoplasmas) inT. grandiflorum with virescent petals. The means of transmission was not established butleafhoppers were suspected.[86] As of November 2021[update], the insectvector forTrillium greening disorder is unknown.
Phytoplasmas were positively identified inT. grandiflorum andT. 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.[87] This subgroup of phytoplasmas is associated with various other diseases, includingmilkweed yellows,Vacciniumwitches' broom, and potato purple top.[88]
Picking parts off a trillium plant can kill it even if the rhizome is left undisturbed.[89] 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 ofMichigan[89] andMinnesota[90] it is illegal to pick trilliums. In New York it is illegal to pick thered trillium.[91]
In 2009, theOntario Trillium Protection Act, a Private Members Bill, was proposed in theOntario legislature that would have made it illegal to in any way injure the commonTrillium grandiflorum (white trillium) in the province (with some exceptions), however the bill was never passed.[92] The rareTrillium flexipes (drooping trillium) is also protected by law in Ontario, because of its decreasing Canadian population.[93]
Highwhite-tailed deer population density has been shown to decrease or eliminate trillium in an area, particularly white trillium.[94] As such height of trillium can be used as an indicator for white-tailed deer population density within forested and urban areas to help forest regeneration.[95]
Some species are harvested from the wild to an unsustainable degree. This is particularly dire in the case ofT. govanianum, whose high selling price as a folk medicine has motivated harvesters to destroy swathes of ecologically sensitive Himalayan forests, causing mudslides.[96]
Several species containsapogenins. They have been used traditionally asuterine 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.[97]
Citizen scientists regularly report observations ofTrillium species from around the world.T. grandiflorum,T. erectum, andT. ovatum (in that order) are the most often observedTrillium species.[99]
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