View source for Trillium

{{Short description|Genus of flowering plants}}
{{Redirect|Toadshade||list of plants known as toadshade}}
{{Other uses}}
{{Use dmy dates|date=January 2026}}
{{Automatic taxobox
|image = TrilliumErectum.jpg
|image_caption = ''[[Trillium erectum]]'' (red trillium)
|taxon = Trillium
|authority = [[Carl Linnaeus|L.]]
|type_species = ''[[Trillium cernuum]]''
|type_species_authority = [[Carl Linnaeus|L.]]{{r|Tropicos}}
|synonyms = 
{{Collapsible list |title=''Trillium'' |{{Genus list
 |Delostylis |Raf.
 |Esdra |Salisb.
 |Huxhamia |Garden
 |Phyllantherum |Raf.
 |Trillidium |Kunth
}}}}
|synonyms_ref ={{r|POWO:24857-1}}
}}

'''''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,<ref name="FNA 133668">{{eFloras |1 |133668 |Trillium |volume=26 |last=Case |first=Frederick W. Jr. }}</ref><ref name="FOC 133668">{{eFloras |2 |133668 |Trillium |volume=24 |last1=Liang |first1=Songyun |last2=Soukup |first2=Victor G. }}</ref> with the greatest diversity of species found in the southern [[Appalachian Mountains]] in the southeastern United States.<ref name="USFS">{{cite web |title=Trilliums Species |url=https://www.fs.fed.us/wildflowers/beauty/trilliums/species.shtml |publisher=[[United States Forest Service]] |access-date=25 June 2019 }}</ref><ref name="BONAP county">{{BONAP |genus=Trillium |date=2014 |access-date=10 August 2019 }}</ref>

==Description==

Plants of this genus are [[Perennial plant|perennial]] [[Herbaceous plant|herbs]] growing from [[rhizome]]s. There are three large leaf-like [[bract]]s arranged in a whorl about a [[Scape (botany)|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 [[sepal]]s and three [[petal]]s in shades of red, purple, pink, white, yellow, or green. At the center of the flower there are six [[stamen]]s and three [[gynoecium|stigmas]] borne on a very short style, if any. The fruit is fleshy and capsule-like or berrylike. The seeds have large, oily [[elaiosome]]s.<ref name="FNA 133668" /><ref name="FOC 133668" />

Occasionally individuals have four-fold symmetry, with four bracts (leaves), four sepals, and four petals in the blossom.<ref>Kevin Kirkland, [https://www.post-gazette.com/life/garden/2013/05/11/Two-4-petaled-trilliums-found/stories/201305110145 Two 4-petaled trilliums found], Pittsburgh Post-Gazette, 11 May 2013; ''Trillium erectum'' and ''Trillium grandiflorum'' examples are given.</ref>{{Better source needed|date=July 2019}}. The [[tetramerous]] condition has been described for several species of ''Trillium'' including ''T.&nbsp;chloropetalum'', ''T.&nbsp;erectum'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;maculatum'', ''T.&nbsp;sessile'', and ''T.&nbsp;undulatum''.{{r|Shaver 1959}}

==Taxonomy==

In 1753, Swedish botanist [[Carl Linnaeus]] established the genus ''Trillium'' by recognizing three species, ''Trillium cernuum'', ''Trillium erectum'', and ''Trillium sessile''.{{sfnp|Case|Case|1997|p=16}} The [[Type (biology)|type specimen]] ''Trillium cernuum'' described by Linnaeus was actually ''Trillium catesbaei'',{{sfnp|Barksdale|1938|pp=271-273}} 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]].{{r|Patrick 2007}} By 1981 [[Liliaceae]] had grown to about 280&nbsp;genera and 4,000&nbsp;species.<ref name="FNA 10507">{{eFloras |1 |10507 |Liliaceae |volume=26 |last=Utech |first=Frederick H. }}</ref> As it became clearer that the very large version of Liliaceae was [[Polyphyly|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 close relative ''[[Paris (plant)|Paris]]'', to the family Melanthiaceae.<ref name=ZomlWillWhitJudd01>{{cite journal |last1=Zomlefer |first1=Wendy B. |last2=Williams |first2=Norris H. |last3=Whitten |first3=W. Mark |last4=Judd |first4=Walter S. |year=2001 |title=Generic Circumscription and Relationships in the Tribe Melanthieae (Liliales, Melanthiaceae), with Emphasis on Zigadenus: Evidence from ITS and trnL-F Sequence Data |journal=American Journal of Botany |volume=88 |issue=9 |pages=1657–1669 |doi=10.2307/3558411 |jstor=3558411 |pmid=21669700 |bibcode=2001AmJB...88.1657Z }}</ref> 
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.{{sfnp|Weakley|2020|p=201}}

In 1850, German botanist [[Carl Sigismund Kunth]] [[Segregate (taxonomy)|segregated]] ''Trillium govanianum'' {{small|Wall. ex D.Don}} into genus ''Trillidium''.{{r|Kunth 1850}} Some authorities consider ''Trillidium'' {{small|Kunth}} to be a synonym for ''Trillium'' {{small|L.}},{{r|POWO:24856-1}} while others recognize the taxon ''Trillidium govanianum'' {{small|(Wall. ex D.Don) Kunth}} based on morphological differences (with other ''Trillium'' species) and molecular evidence.{{sfnp|Case|Case|1997|p=245}}{{r|Farmer and Schilling 2002}} Still others support the segregation of ''Trillium undulatum'' {{small|Willd.}} into genus ''Trillidium'' alongside ''Trillidium govanianum''.{{sfnp|Weakley|2020|p=201}}{{r|Weakley et al. 2018}}

==Subdivisions==
All names used in this section are taken from the [[International Plant Names Index]].<ref>{{IPNI |search=Trillium |accessdate=8 October 2019 }}</ref> {{As of|February 2022}}, [[Plants of the World Online]] (POWO) accepts 49&nbsp;species and 5&nbsp;named hybrids,{{r|POWO:24857-1}} all of which are listed below. The geographical locations are taken from POWO and the [[Flora of North America]],<ref name="FNA 133668" /> except where noted.

The ''Trillium'' genus has traditionally been divided into two [[Subgenus|subgenera]], ''Trillium'' subgenus ''Trillium'' and ''Trillium'' subgenus ''Phyllantherum'', based on whether the flower is [[Pedicel (botany)|pedicellate]] or [[Sessility (botany)|sessile]].{{r|FNA:312202|FNA:312201}} At the time, the former subgenus was considered to be the more primitive group.{{sfnp|Freeman|1975|p=2}}{{sfnp|Case|Case|1997|p=19}}{{r|FNA 133668}} Based on [[molecular systematics]], ''Trillium'' subgen.&nbsp;''Phyllantherum'' has been shown to be a [[Monophyly|monophyletic]] group, but its segregation renders the remaining ''Trillium'' subgen.&nbsp;''Trillium'' [[Paraphyly|paraphyletic]].{{r|Farmer 2006}}

''Trillium'' subgenus ''Phyllantherum'' was named by [[Constantine Samuel Rafinesque]] in 1820,{{r|IPNI:60464242-2}} but since he did not provide a description, the name was declared invalid in 2014.{{r|Reveal and Gandhi 2014a}} At that time, the correct name was thought to be ''Trillium'' subgen.&nbsp;''Sessilium'',{{r|Reveal and Gandhi 2014b}} which was described by Rafinesque in 1830. However, that name was later found to be incorrect as well.{{sfnp|Lampley|Gereau|Floden|Schilling|2022|p=279}} {{As of|July 2022}}, the correct name of the subgenus is ''Trillium'' {{small|L.}} subgen.&nbsp;''Sessilia'' {{small|Raf.}}{{r|IPNI:60464602-2}} Its [[type species]] is ''Trillium sessile'' {{small|L.}}

In 1819, Rafinesque described and named the genus ''Delostylis'',{{r|IPNI:24183-1}} and then placed ''Trillium stylosum'' {{small|Nutt.}} (now a synonym for ''Trillium catesbaei'' {{small|Elliott}}) into the new genus. Reversing himself a decade later, Rafinesque instead placed ''Trillium stylosum'' into a new subgenus ''Delostylium'' in 1830.{{r|Rafinesque 1830}} Presumably Rafinesque had intended the subgeneric name to replace the earlier generic name, and so the correct name of the former is ''Trillium'' {{small|L.}} subgen.&nbsp;''Delostylis'' {{small|(Raf.) Raf.}}.{{r|IPNI:60464604-2}}{{sfnp|Lampley|Gereau|Floden|Schilling|2022|p=279}} Its type species is ''Trillium catesbaei''. Historically, the subgenus has been known as the Catesbaei group.{{sfnp|Gleason|1906}}{{sfnp|Farmer|2007|pp=3-4}} The word ''Delostylis'' means "with a small but conspicuous style".{{sfnp|Gledhill|2008|pp=137,219,364}}

Based on [[morphology (biology)|morphology]] and [[genetic analysis|molecular evidence]], a few taxa in genus ''Trillium'' have been [[Segregate (taxonomy)|segregated]] into other genera:

* ''Trillium rivale'', first described in 1885, was segregated into genus ''Pseudotrillium'' {{small|S.B.Farmer}} in 2002.{{r|Farmer and Schilling 2002}} The name ''Pseudotrillium rivale'' {{small|(S.Watson) S.B.Farmer}} is widely recognized.
* ''Trillium govanianum'', first described in 1839, was segregated into genus ''Trillidium'' {{small|Kunth}} in 1850.{{r|Kunth 1850}} However, the name ''Trillidium govanianum'' {{small|(Wall. ex D.Don) Kunth}} is not widely recognized.
* ''Trillium undulatum'', first described in 1801, was segregated into genus ''Trillidium'' in 2018,{{r|Weakley et al. 2018}} but the name ''Trillidium undulatum'' {{small|(Willd.) Floden & E.E.Schill.}} is controversial and not widely recognized.

[[Phylogenetic analysis]] places ''Trillidium govanianum'' and ''Trillidium undulatum'' together in a clade with high support.{{sfnp|Lampley|2021|pp=15-17}} However, since ''Trillium'' and ''Trillidium'' are both individually and collectively monophyletic, it is a matter of choice whether or not to recognize genus ''Trillidium''.

Excluding the segregate taxa listed above, the remaining taxa separate into four clades with the following names:{{sfnp|Lampley|Gereau|Floden|Schilling|2022|p=279}}

* ''Trillium'' {{small|L.}} subgen.&nbsp;''Trillium''
* ''Trillium'' {{small|L.}} subgen.&nbsp;''Callipetalon'' {{small|Lampley & E.E.Schill.}}
* ''Trillium'' {{small|L.}} subgen.&nbsp;''Delostylis'' {{small|(Raf.) Raf.}} [as '''Delostylium''']
* ''Trillium'' {{small|L.}} subgen.&nbsp;''Sessilia'' {{small|Raf.}} [as '''Sessilium''']

Traditionally, ''Trillium'' subgen.&nbsp;''Trillium'' has included '''all''' pedicellate-flowered species (which is a [[paraphyletic]] group), but in 2022, the subgenus was [[Circumscription (taxonomy)|circumscribed]] as a [[clade]] of fourteen (14) species.{{sfnp|Lampley|Gereau|Floden|Schilling|2022|pp=280-281}} Its type species is ''Trillium erectum'' {{small|L.}} Historically, the subgenus has been known as the Erectum group.{{sfnp|Gleason|1906}}{{sfnp|Barksdale|1938}}{{sfnp|Case|Case|1997|pp=67-71}}{{sfnp|Farmer|2007|pp=3-4}}{{sfnp|Lampley|2021}}

''Trillium'' subgen.&nbsp;''Callipetalon'' was described by Jayne A.&nbsp;Lampley and Edward E.&nbsp;Schilling in 2022.{{r|IPNI:77301132-1}} The word ''Callipetalon'' means "beautiful petal", a reference to "the famously beautiful flowers" of its type species, ''Trillium grandiflorum'' {{small|(Michx.) Salisb.}}{{sfnp|Lampley|Gereau|Floden|Schilling|2022|p=281}} Historically, the subgenus has been known as the Grandiflorum group.{{sfnp|Gleason|1906}}{{sfnp|Barksdale|1938}}{{sfnp|Case|Case|1997|pp=67-71}}{{sfnp|Farmer|2007|pp=3-4}}{{sfnp|Lampley|2021}}

This leads to a four-part concept of ''Trillium'' that sharply contrasts with the traditional pedicellate vs.&nbsp;sessile dichotomy outlined previously.{{sfnp|Lampley|2021|loc=Ch.&nbsp;1}}

===Subgenus ''Trillium''===
''Trillium'' subgen.&nbsp;''Trillium'', the '''Erectum group''', is a group of pedicellate-flowered trilliums that includes ''[[Trillium erectum]]''. The subgenus was [[Circumscription (taxonomy)|circumscribed]] as a [[clade]] of fourteen (14) species in 2022.{{sfnp|Lampley|Gereau|Floden|Schilling|2022|pp=280-281}} Species in this subgenus have [[Pedicel (botany)|pedicellate]] flowers (on a stalk) with three distinct [[Stigma (botany)|stigma]]s (no [[Stigma (botany)#Style|style]]) 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).

{{div col}}
* ''[[Trillium apetalon]]'' {{small|Makino}}{{r|POWO:542515-1}}<ref>{{cite journal |last1=Makino |first1=T. |title=Observations on the Flora of Japan |journal=Botanical Magazine (Tokyo) |date=1910 |volume=24 |issue=282 |page=137 |url=https://biodiversitylibrary.org/page/41540964 |access-date=3 August 2019 |doi=10.15281/jplantres1887.24.282_137 |doi-access=free }}</ref><ref>{{cite web |title=''Trillium apetalon'' |url=https://www.keepingitgreennursery.com/products/trillium-smallii-kojima-island-trillium |website=Keeping It Green Nursery |access-date=3 August 2019 |archive-date=3 August 2019 |archive-url=https://web.archive.org/web/20190803214246/https://www.keepingitgreennursery.com/products/trillium-smallii-kojima-island-trillium |url-status=dead }}</ref> – Japan, Kuril Islands, E Russia (Sakhalin)
* ''[[Trillium camschatcense]]'' {{small|Ker Gawl.}}{{r|POWO:328445-2}}<ref name="FOC 200027980">{{eFloras |2 |200027980 |Trillium camschatcense |volume=24 |last1=Liang |first1=Songyun |last2=Soukup |first2=Victor G. }}</ref> – NE China (Jilin), Japan, Korea, Kuril Islands, E Russia (Primorsky Krai, Khabarovsk Krai, Kamchatka Peninsula, Sakhalin)
* ''[[Trillium cernuum]]'' {{small|L.}} – 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 channellii]]'' {{small|Fukuda, J.D.Freeman & Itou}}{{r|POWO:989638-1}}<ref>{{cite journal |last1=Fukuda |first1=Ichiro |last2=Freeman |first2=John D. |last3=Itou |first3=Masakazu |title=''Trillium channellii'', sp. nov. (Trilliaceae), in Japan, and ''T. camschatcense'' Ker Gawler, Correct Name for the Asiatic diploid ''Trillium'' |journal=Novon |date=1996 |volume=6 |issue=2 |pages=164–171 |url=https://biodiversitylibrary.org/page/661889 |doi=10.2307/3391914 |jstor=3391914 |bibcode=1996Novon...6..164F }}</ref> – Japan (E Hokkaido)
* ''[[Trillium erectum]]'' {{small|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]]'' {{small|Raf.}} – Ontario; Alabama, Arkansas,<ref name="BONAP county"/> Delaware, Illinois, Indiana, Iowa, Kentucky, Maryland,<ref name="BONAP county"/> Michigan, Minnesota, Missouri, New York, Ohio, Pennsylvania, South Dakota, Tennessee, Virginia, West Virginia, Wisconsin
* [[Trillium × hagae|''Trillium'' × ''hagae'']] {{small|Miyabe & Tatew.}}{{r|POWO:542554-1}} (''Trillium camschatcense'' × ''Trillium tschonoskii'') – Japan, E Russia (S Sakhalin)
* ''[[Trillium hibbersonii]]'' {{small|(T.M.C.Taylor & Szczaw.) D.O'Neill & S.B.Farmer}} – British Columbia
* [[Trillium × komarovii|''Trillium'' × ''komarovii'']] {{small|H.Nakai & Koji Ito}}{{r|POWO:961664-1}} (''Trillium camschatcense'' × unknown) – Japan, E Russia (Primorsky Krai)
* [[Trillium × miyabeanum|''Trillium'' × ''miyabeanum'']] {{small|Tatew. ex J.Samej.}}{{r|POWO:542571-1}} (''Trillium apetalon'' × ''Trillium tschonoskii'') – Japan
* ''[[Trillium rugelii]]'' {{small|Rendle}} – Alabama, Georgia, North Carolina, South Carolina, Tennessee
* ''[[Trillium simile]]'' {{small|Gleason}} – Georgia, North Carolina, Tennessee
* ''[[Trillium smallii]]'' {{small|Maxim.}}{{r|POWO:542604-1}} – Japan, E Russia (S Sakhalin)
* ''[[Trillium sulcatum]]'' {{small|T.S.Patrick}} – Alabama, Georgia, Kentucky, North Carolina, Tennessee, Virginia, West Virginia
* ''[[Trillium taiwanense]]'' {{small|S.S.Ying}}{{r|POWO:937303-1}}<ref name="FOC 240001618">{{eFloras |2 |240001618 |Trillium taiwanense |volume=24 |last1=Liang |first1=Songyun |last2=Soukup |first2=Victor G. }}</ref> – E Taiwan
* ''[[Trillium tschonoskii]]'' {{small|Maxim.}}{{r|POWO:542611-1}}<ref name="FOC 200027981">{{eFloras |2 |200027981 |Trillium tschonoskii |volume=24 |last1=Liang |first1=Songyun |last2=Soukup |first2=Victor G. }}</ref> – Bhutan, China (Anhui, Fujian, Gansu, Hubei, Shaanxi, Sichuan, Tibet Autonomous Region, Yunnan, Zhejiang), NE India (Sikkim), Japan, Korea, Kuril Islands, Myanmar, Russia (Sakhalin), Taiwan
* ''[[Trillium vaseyi]]'' {{small|Harb.}} – Alabama, Georgia, North Carolina, South Carolina, Tennessee
* [[Trillium × yezoense|''Trillium'' × ''yezoense'']] {{small|Tatew. ex J.Samej.}}{{r|POWO:542620-1}} (''Trillium apetalon'' × ''Trillium camschatcense'') – Japan
{{div col end}}

===Subgenus ''Callipetalon''===
''Trillium'' subgen.&nbsp;''Callipetalon'', the '''Grandiflorum group''', is a group of pedicellate-flowered trilliums that includes ''[[Trillium grandiflorum]]''. The subgenus was [[Circumscription (taxonomy)|circumscribed]] as a [[clade]] of three (3) species in 2022.{{sfnp|Lampley|Gereau|Floden|Schilling|2022|p=281}} Species in the subgenus have [[Pedicel (botany)|pedicellate]] flowers (on a stalk) and solid green leaves (except ''T.&nbsp;ovatum'' on the west coast of California, which occasionally has mottled leaves). The [[Stigma (botany)|stigma]]s are fused together at their bases (basally [[Connation|connate]]) but lack a definite [[Stigma (botany)#Style|style]]. They are distributed across North America (but not Asia). Flowers were and still are consumed and used by [[Indigenous peoples of the Americas|indigenous peoples]] in various regions of North America.

{{div col}}
* ''[[Trillium crassifolium]]'' {{small|Piper}} – Washington
* ''[[Trillium grandiflorum]]'' {{small|(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 nivale]]'' {{small|Riddell}} – Illinois, Indiana, Iowa, Kentucky, Maryland, Michigan, Minnesota, Missouri, Nebraska, Ohio, Pennsylvania, South Dakota, West Virginia, Wisconsin
* ''[[Trillium ovatum]]'' {{small|Pursh}} – Alberta, British Columbia; California, Colorado, Idaho, Montana, Oregon, Washington, Wyoming
* ''[[Trillium scouleri]]'' {{small|Rydb. ex Gleason}} – Alberta, British Columbia; Colorado, Idaho, Montana, Washington, Wyoming
{{div col end}}

===Subgenus ''Delostylis''===
''Trillium'' subgen.&nbsp;''Delostylis'', the '''Catesbaei group''', is a group of pedicellate-flowered trilliums that includes ''[[Trillium catesbaei]]''. The subgenus was [[Circumscription (taxonomy)|circumscribed]] as a [[clade]] of seven (7) species in 2022.{{sfnp|Lampley|Gereau|Floden|Schilling|2022|pp=281-282}} Species in this subgenus have [[Pedicel (botany)|pedicellate]] flowers (except for one variety of ''T.&nbsp;pusillum'') with a definite [[Stigma (botany)#Style|style]] and solid green leaves (not mottled). Distribution is restricted to the southeastern and south central United States.

{{div col}}
* ''[[Trillium catesbaei]]'' {{small|Elliott}} – Alabama, Georgia, North Carolina, South Carolina, Tennessee
* ''[[Trillium georgianum]]'' {{small|S.B.Farmer}} – Georgia
* ''[[Trillium persistens]]'' {{small|W.H.Duncan}} – Georgia, South Carolina
* ''[[Trillium pusillum]]'' {{small|Michx.}} – Alabama, Arkansas, Kentucky, Maryland, Mississippi, Missouri, North Carolina, Oklahoma, South Carolina, Tennessee, Virginia, West Virginia
* ''[[Trillium texanum]]'' {{small|Buckley}} – Arkansas, Louisiana, Texas
{{div col end}}

===Subgenus ''Sessilia''===
''Trillium'' subgen.&nbsp;''Sessilia'', the '''sessile-flowered trilliums''', is a group of species that includes ''[[Trillium sessile]]''. The subgenus was [[Circumscription (taxonomy)|circumscribed]] as a [[clade]] of twenty-six (26) species in 2022.{{sfnp|Lampley|Gereau|Floden|Schilling|2022|p=282}} Species in this subgenus have [[Sessility (botany)|sessile]] flowers (no flower stalk), erect petals (except in ''T.&nbsp;stamineum''), and mottled leaves (except in ''T.&nbsp;petiolatum'' and occasionally in plants of other sessile-flowered species).{{r|FNA:312201}}

{{div col}}
* ''[[Trillium albidum]]'' {{small|J.D.Freeman}} – California, Oregon, Washington
* ''[[Trillium angustipetalum]]'' {{small|(Torr.) J.D.Freeman}} – California
* ''[[Trillium chloropetalum]]'' {{small|(Torr.) Howell}} – California
* ''[[Trillium cuneatum]]'' {{small|Raf.}} – Alabama, Georgia, Kentucky, Mississippi, North Carolina, South Carolina, Tennessee
* ''[[Trillium decipiens]]'' {{small|J.D.Freeman}} – Alabama, Florida, Georgia
* ''[[Trillium decumbens]]'' {{small|Harb.}} – Alabama, Georgia, Tennessee
* ''[[Trillium delicatum]]'' {{small|Floden & E.E.Schill.}} – Georgia
* ''[[Trillium discolor]]'' {{small|Hook.}} – Georgia, North Carolina, South Carolina
* ''[[Trillium foetidissimum]]'' {{small|J.D.Freeman}} – Louisiana, Mississippi
* ''[[Trillium gracile]]'' {{small|J.D.Freeman}} – Louisiana, Texas
* ''[[Trillium kurabayashii]]'' {{small|J.D.Freeman}} – California, Oregon
* ''[[Trillium lancifolium]]'' {{small|Raf.}} – Alabama, Florida, Georgia, South Carolina, Tennessee
* ''[[Trillium ludovicianum]]'' {{small|Harb.}} – Louisiana, Mississippi, Texas
* ''[[Trillium luteum]]'' {{small|(Muhl.) Harb.}} – District of Columbia, Georgia, Kentucky, North Carolina, Tennessee
* ''[[Trillium maculatum]]'' {{small|Raf.}} – Alabama, Florida, Georgia, South Carolina
* ''[[Trillium oostingii]]'' {{small|Gaddy}} – South Carolina<ref name="BONAP county"/>
* ''[[Trillium petiolatum]]'' {{small|Pursh}} – Idaho, Oregon, Washington
* ''[[Trillium recurvatum]]'' {{small|L.C.Beck}} – Alabama, Arkansas, Illinois, Indiana, Iowa, Kentucky, Louisiana, Michigan, Mississippi, Missouri, Ohio, Tennessee, Texas, Wisconsin
* ''[[Trillium reliquum]]'' {{small|J.D.Freeman}} – Georgia, South Carolina
* ''[[Trillium sessile]]'' {{small|L.}} – Alabama, Arkansas, District of Columbia, Illinois, Indiana, Kansas, Kentucky, Maryland, Michigan, Missouri, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, Tennessee, Virginia, West Virginia
* ''[[Trillium stamineum]]'' {{small|Harb.}} – Alabama, Mississippi, Tennessee
* ''[[Trillium tennesseense]]'' {{small|E. E. Schill & Floden}} – Tennessee
* ''[[Trillium underwoodii]]'' {{small|Small}} – Alabama, Florida, Georgia
* ''[[Trillium viride]]'' {{small|L.C.Beck}} – Illinois, Missouri
* ''[[Trillium viridescens]]'' {{small|Nutt.}} – Arkansas, Kansas, Missouri, Oklahoma, Texas
{{div col end}}

===Ungrouped taxa===

The following pair of taxa do not fit into any of the above groups since they are markedly different from other ''Trillium'' species. There is evidence to support the segregation of these species into a separate genus (''Trillidium'') but the proposal is controversial.

{{div col}}
* ''[[Trillium govanianum]]'' {{small|Wall. ex D.Don}}{{r|POWO:542551-1|FOC 200027979|FOP 133668}} – NE Afghanistan, Bhutan, China (Tibet Autonomous Region, Yunnan), N + NE India (Himachal Pradesh, Jammu and Kashmir, Sikkim, Uttarakhand), Nepal, N Pakistan
* ''[[Trillium undulatum]]'' {{small|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
{{div col end}}

===Other taxa===

{{As of|April 2023}}, [[Plants of the World Online]] does not accept these taxa:

* ''Trillium parviflorum'' {{small|V.G.Soukup}} is an accepted name by some authorities<ref name="FNA 242102003">{{eFloras |1 |242102003 |Trillium parviflorum |volume=26 |last=Case |first=Frederick W. Jr.|access-date=23 July 2019 }}</ref> while others regard this name as a synonym of [[Trillium albidum|''T.&nbsp;albidum'']] subsp. ''parviflorum'' {{small|(V.G.Soukup) K.L.Chambers & S.C.Meyers}}.{{r|POWO:258353-2}}

The following taxa are of historical interest:

* ''Trillium rivale'' {{small|S.Watson}}<ref name="FNA 242102009">{{eFloras |1 |242102009 |Trillium rivale |volume=26 |last=Case |first=Frederick W. Jr. |access-date=16 July 2019 }}</ref> has been segregated to a [[Monotypic taxon|monotypic]] genus as ''[[Pseudotrillium rivale]]'' {{small|(S.Watson) S.B.Farmer}}.{{r|Farmer and Schilling 2002}}
* ''Trillium'' ×&nbsp;''crockerianum'' {{small|Halda}} was originally described as a hybrid with parents ''Trillium ovatum'' and ''Trillium rivale'',{{r|IPNI:1015183-1}} but since the latter is now a member of genus ''[[Pseudotrillium]]'', the hybrid has become an undescribed [[intergeneric hybrid]], and therefore its taxonomic placement is uncertain.{{r|POWO:1015183-1}}

==Distribution==

''Trillium'' species are native to North America and Asia.<ref name="FNA 133668" /><ref name="FOC 133668" /><ref name="BONAP state">{{BONAP |genus=Trillium |state=1 |date=2014 |access-date=10 August 2019 }}</ref>

===North America===

More than three dozen ''Trillium'' species are found in North America,<ref name="FNA 133668" /> most of which are native to eastern North America. Just six species are native to western North America: ''T.&nbsp;albidum'', ''T.&nbsp;angustipetalum'', ''T.&nbsp;chloropetalum'', ''T.&nbsp;kurabayashii'', ''T.&nbsp;ovatum'', and ''T.&nbsp;petiolatum''. Of these, only ''T.&nbsp;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.<ref name="FNA 133668" />

{{div col}}
* [[Alberta]]: ''T.&nbsp;ovatum'', ''T.&nbsp;scouleri''
* [[British Columbia]]: ''T.&nbsp;hibbersonii'', ''T.&nbsp;ovatum'', ''T.&nbsp;scouleri''
* [[Manitoba]]: ''T.&nbsp;cernuum''
* [[New Brunswick]]: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;undulatum''
* [[Newfoundland (island)|Newfoundland]]: ''T.&nbsp;cernuum''
* [[Northwest Territories]]: none
* [[Nova Scotia]]: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;undulatum''
* [[Nunavut]]: none
* [[Ontario]]: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;flexipes'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;undulatum''
* [[Prince Edward Island]]: ''T.&nbsp;cernuum'', ''T.&nbsp;undulatum''
* [[Quebec]]: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;undulatum''
* [[Saskatchewan]]: ''T.&nbsp;cernuum''
* [[Yukon]]: none
{{div col end}}

====United States====

Except for the desert regions of the southwestern United States, ''Trillium'' species are found throughout the [[Contiguous United States|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.<ref name="FNA 133668" /> The state of Georgia is home to 21&nbsp;species of trillium.

{{div col}}
* [[Alabama]]:{{sfnp|Spaulding|Kartesz|Horne|Finzel|2021|pp=24-59}} ''T.&nbsp;catesbaei'', ''T.&nbsp;cuneatum'', ''T.&nbsp;decipiens'', ''T.&nbsp;decumbens'', ''T.&nbsp;flexipes'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;lancifolium'', ''T.&nbsp;luteum'', ''T.&nbsp;maculatum'', ''T.&nbsp;pusillum'', ''T.&nbsp;recurvatum'', ''T.&nbsp;reliquum'', ''T.&nbsp;rugelii'', ''T.&nbsp;sessile'', ''T.&nbsp;stamineum'', ''T.&nbsp;sulcatum'', ''T.&nbsp;underwoodii'', ''T.&nbsp;vaseyi''
* [[Alaska]]: none
* [[Arizona]]: none
* [[Arkansas]]: ''T.&nbsp;flexipes'', ''T.&nbsp;pusillum'', ''T.&nbsp;recurvatum'', ''T.&nbsp;sessile'', ''T.&nbsp;texanum'', ''T.&nbsp;viridescens''
* California: ''T.&nbsp;albidum'', ''T.&nbsp;angustipetalum'', ''T.&nbsp;chloropetalum'', ''T.&nbsp;kurabayashii'', ''T.&nbsp;ovatum''
* [[Colorado]]: ''T.&nbsp;ovatum'', ''T.&nbsp;scouleri''
* [[Connecticut]]: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;undulatum''
* [[Delaware]]: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;flexipes'', ''T.&nbsp;grandiflorum''
* [[Washington, D.C.|District of Columbia]]:{{r|Shetler and Orli 2002}} ''T.&nbsp;grandiflorum'', ''T.&nbsp;luteum'', ''T.&nbsp;sessile''
* Florida: ''T.&nbsp;decipiens'', ''T.&nbsp;lancifolium'', ''T.&nbsp;maculatum'', ''T.&nbsp;underwoodii''
* [[Georgia (U.S. state)|Georgia]]: ''T.&nbsp;catesbaei'', ''T.&nbsp;cuneatum'', ''T.&nbsp;decipiens'', ''T.&nbsp;decumbens'', ''T.&nbsp;delicatum'', ''T.&nbsp;discolor'', ''T.&nbsp;erectum'', ''T.&nbsp;georgianum'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;lancifolium'', ''T.&nbsp;luteum'', ''T.&nbsp;maculatum'', ''T.&nbsp;persistens'', ''T.&nbsp;reliquum'', ''T.&nbsp;rugelii'', ''T.&nbsp;simile'', ''T.&nbsp;sulcatum'', ''T.&nbsp;underwoodii'', ''T.&nbsp;undulatum'', ''T.&nbsp;vaseyi''
* Hawaii: none
* [[Idaho]]: ''T.&nbsp;ovatum'', ''T.&nbsp;petiolatum'', ''T.&nbsp;scouleri''
* [[Illinois]]: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;flexipes'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;nivale'', ''T.&nbsp;recurvatum'', ''T.&nbsp;sessile'', ''T.&nbsp;viride''
* [[Indiana]]: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;flexipes'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;nivale'', ''T.&nbsp;recurvatum'', ''T.&nbsp;sessile''
* [[Iowa]]: ''T.&nbsp;cernuum'', ''T.&nbsp;flexipes'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;nivale'', ''T.&nbsp;recurvatum''
* [[Kansas]]: ''T.&nbsp;sessile'', ''T.&nbsp;viridescens''
* [[Kentucky]]: ''T.&nbsp;cuneatum'', ''T.&nbsp;erectum'', ''T.&nbsp;flexipes'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;luteum'', ''T.&nbsp;nivale'', ''T.&nbsp;pusillum'', ''T.&nbsp;recurvatum'', ''T.&nbsp;sessile'', ''T.&nbsp;sulcatum'', ''T.&nbsp;undulatum''
* [[Louisiana]]: ''T.&nbsp;foetidissimum'', ''T.&nbsp;gracile'', ''T.&nbsp;ludovicianum'', ''T.&nbsp;recurvatum'', ''T.&nbsp;texanum''
* [[Maine]]: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;undulatum''
* [[Maryland]]: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;flexipes'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;nivale'', ''T.&nbsp;pusillum'', ''T.&nbsp;sessile'', ''T.&nbsp;undulatum''
* [[Massachusetts]]: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;undulatum''
* [[Michigan]]: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;flexipes'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;nivale'', ''T.&nbsp;recurvatum'', ''T.&nbsp;sessile'', ''T.&nbsp;undulatum''
* [[Minnesota]]: ''T.&nbsp;cernuum'', ''T.&nbsp;flexipes'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;nivale''
* [[Mississippi]]: ''T.&nbsp;cuneatum'', ''T.&nbsp;foetidissimum'', ''T.&nbsp;ludovicianum'', ''T.&nbsp;pusillum'', ''T.&nbsp;recurvatum'', ''T.&nbsp;stamineum''
* [[Missouri]]: ''T.&nbsp;flexipes'', ''T.&nbsp;nivale'', ''T.&nbsp;pusillum'', ''T.&nbsp;recurvatum'', ''T.&nbsp;sessile'', ''T.&nbsp;viride'', ''T.&nbsp;viridescens''
* [[Montana]]: ''T.&nbsp;ovatum'', ''T.&nbsp;scouleri''
* [[Nebraska]]: ''T.&nbsp;nivale''
* [[Nevada]]: none
* [[New Hampshire]]: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;undulatum''
* [[New Jersey]]: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;undulatum''
* [[New Mexico]]: none
* New York: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;flexipes'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;sessile'', ''T.&nbsp;undulatum''
* [[North Carolina]]: ''T.&nbsp;catesbaei'', ''T.&nbsp;cuneatum'', ''T.&nbsp;discolor'', ''T.&nbsp;erectum'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;luteum'', ''T.&nbsp;pusillum'', ''T.&nbsp;rugelii'', ''T.&nbsp;sessile'', ''T.&nbsp;simile'', ''T.&nbsp;sulcatum'', ''T.&nbsp;undulatum'', ''T.&nbsp;vaseyi''
* [[North Dakota]]: ''T.&nbsp;cernuum''
* [[Ohio]]: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;flexipes'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;nivale'', ''T.&nbsp;recurvatum'', ''T.&nbsp;sessile'', ''T.&nbsp;undulatum''
* [[Oklahoma]]: ''T.&nbsp;pusillum'', ''T.&nbsp;sessile'', ''T.&nbsp;viridescens''
* [[Oregon]]: ''T.&nbsp;albidum'', ''T.&nbsp;kurabayashii'', ''T.&nbsp;ovatum'', ''T.&nbsp;petiolatum''
* [[Pennsylvania]]: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;flexipes'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;nivale'', ''T.&nbsp;sessile'', ''T.&nbsp;undulatum''
* [[Rhode Island]]: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;undulatum''
* [[South Carolina]]: ''T.&nbsp;catesbaei'', ''T.&nbsp;cuneatum'', ''T.&nbsp;discolor'', ''T.&nbsp;erectum'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;lancifolium'', ''T.&nbsp;maculatum'', ''T.&nbsp;oostingii'', ''T.&nbsp;persistens'', ''T.&nbsp;pusillum'', ''T.&nbsp;reliquum'', ''T.&nbsp;rugelii'', ''T.&nbsp;undulatum'', ''T.&nbsp;vaseyi''
* [[South Dakota]]: ''T.&nbsp;cernuum'', ''T.&nbsp;flexipes'', ''T.&nbsp;nivale''
* [[Tennessee]]: ''T.&nbsp;catesbaei'', ''T.&nbsp;cuneatum'', ''T.&nbsp;decumbens'', ''T.&nbsp;erectum'', ''T.&nbsp;flexipes'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;lancifolium'', ''T.&nbsp;luteum'', ''T.&nbsp;pusillum'', ''T.&nbsp;recurvatum'', ''T.&nbsp;rugelii'', ''T.&nbsp;sessile'', ''T.&nbsp;simile'', ''T.&nbsp;stamineum'', ''T.&nbsp;sulcatum'', ''T.&nbsp;tennesseense'', ''T.&nbsp;undulatum'', ''T.&nbsp;vaseyi''
* [[Texas]]: ''T.&nbsp;gracile'', ''T.&nbsp;ludovicianum'', ''T.&nbsp;recurvatum'', ''T.&nbsp;texanum'', ''T.&nbsp;viridescens''
* [[Utah]]: none
* [[Vermont]]: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;undulatum''
* [[Virginia]]: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;flexipes'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;pusillum'', ''T.&nbsp;sessile'', ''T.&nbsp;sulcatum'', ''T.&nbsp;undulatum''
* [[Washington (state)|Washington]]: ''T.&nbsp;albidum'', ''T.&nbsp;ovatum'', ''T.&nbsp;petiolatum'', ''T.&nbsp;scouleri''
* [[West Virginia]]: ''T.&nbsp;cernuum'', ''T.&nbsp;erectum'', ''T.&nbsp;flexipes'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;nivale'', ''T.&nbsp;pusillum'', ''T.&nbsp;sessile'', ''T.&nbsp;sulcatum'', ''T.&nbsp;undulatum''
* [[Wisconsin]]: ''T.&nbsp;cernuum'', ''T.&nbsp;flexipes'', ''T.&nbsp;grandiflorum'', ''T.&nbsp;nivale'', ''T.&nbsp;recurvatum''
* [[Wyoming]]: ''T.&nbsp;ovatum'', ''T.&nbsp;scouleri''
{{div col end}}

====Other====

* [[Saint Pierre and Miquelon]]: ''T.&nbsp;cernuum''

===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.

{{div col}}
* Afghanistan: ''T.&nbsp;govanianum''
* Bhutan: ''T.&nbsp;govanianum'', ''T.&nbsp;tschonoskii''
* China:<ref name="FOC 133668" /> ''T.&nbsp;camschatcense'' ([[Jilin]]), ''T.&nbsp;govanianum'' ([[Tibet Autonomous Region]], Yunnan), ''T.&nbsp;taiwanense'' (E Taiwan), ''T.&nbsp;tschonoskii'' ([[Anhui]], Fujian, [[Gansu]], Hubei, [[Shaanxi]], Sichuan, Tibet Autonomous Region, Yunnan, [[Zhejiang]])
* India: ''T.&nbsp;govanianum'' ([[Himachal Pradesh]], [[Jammu and Kashmir (union territory)|Jammu and Kashmir]], Sikkim, [[Uttarakhand]]), ''T.&nbsp;tschonoskii'' (Sikkim)
* Japan: ''T.&nbsp;apetalon'', ''T.&nbsp;camschatcense'', ''T.&nbsp;channellii'' ([[Hokkaido]]), {{nowrap|''T.'' × ''hagae''}}, {{nowrap|''T.'' × ''komarovii''}}, {{nowrap|''T.'' × ''miyabeanum''}}, ''T.&nbsp;smallii'', ''T.&nbsp;tschonoskii'', {{nowrap|''T.'' × ''yezoense''}}
* Korea: ''T.&nbsp;camschatcense'', ''T.&nbsp;tschonoskii''
* [[Kuril Islands]]: ''T.&nbsp;apetalon'', ''T.&nbsp;camschatcense'', ''T.&nbsp;tschonoskii''
* Myanmar: ''T.&nbsp;tschonoskii''
* Nepal: ''T.&nbsp;govanianum''
* Pakistan:<ref name="FOP 133668" /> ''T.&nbsp;govanianum''
* Russia: ''T.&nbsp;apetalon'' ([[Sakhalin]]), ''T.&nbsp;camschatcense'' ([[Primorsky Krai]], [[Khabarovsk Krai]], [[Kamchatka Peninsula]], Sakhalin), {{nowrap|''T.'' × ''hagae''}} (Sakhalin), {{nowrap|''T.'' × ''komarovii''}} (Primorsky Krai), ''T.&nbsp;smallii'' (Sakhalin), ''T.&nbsp;tschonoskii'' (Sakhalin)
* Taiwan: ''T.&nbsp;taiwanense'', ''T.&nbsp;tschonoskii''
{{div col end}}

==Identification==

A fully general [[Single-access key|dichotomous key]] requires a mature, flowering plant.<ref name="FNA 133668" />{{sfnp|Case|Case|1997|pp=71-85}}{{sfnp|Barksdale|1938|pp=278-279}}{{sfnp|Freeman|1975|pp=4-6}} The first step is to determine whether or not the flower sits on a [[Pedicel (botany)|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 [[Petiole (botany)|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 [[Glossary of leaf morphology#trifoliate|trifoliate]] leaves but the former lacks 3-way rotational symmetry and has leaf veins unlike those of ''Trillium''.

==Ecology==

Trilliums are [[myrmecochory|myrmecochorous]], that is, [[ant]]s act as agents of [[seed dispersal]]. Each seed of a ripe fruit has a white fleshy appendage called an [[elaiosome]]. 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.{{sfnp|Case|Case|1997|p=26}} 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&nbsp;meter away from the parent plant.

For example, the seeds of ''[[Trillium camschatcense]]'' and ''[[Trillium tschonoskii|T. tschonoskii]]'' are collected by ant species ''[[Aphaenogaster smythiesi]]'' and ''[[Myrmica ruginodis]]''.{{r|Ohara and Higashi 1987}} Sometimes [[beetle]]s interfere with the dispersal process by eating the elaiosomes, which makes the seeds less attractive to ants.

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&nbsp;meters away from the parent plant. Yellow jackets are documented seed dispersers for at least three species of ''Trillium'' (''T.&nbsp;catesbaei'', ''T.&nbsp;cuneatum'', ''T.&nbsp;undulatum'').{{r|Zettler et al. 2001}}

The seeds of some ''Trillium'' species are more attractive to ants than others. Widely distributed species (e.g., ''Trillium grandiflorum'', ''Trillium catesbaei'', and ''Trillium cuneatum'') are more attractive to ants than narrowly endemic species (e.g., ''Trillium lancifolium'', ''Trillium discolor'', and ''Trillium decumbens'').{{r|Miller 2022}}

===Hybrids===
{{As of|February 2022}}, [[Plants of the World Online]] recognizes five named hybrids,{{r|POWO:24857-1}} four in Asia and one in North America. Three of the Asian hybrids, {{nowrap|''T.'' × ''hagae''}}, {{nowrap|''T.'' × ''miyabeanum''}}, and {{nowrap|''T.'' × ''yezoense''}}, are well studied,{{sfnp|Case|Case|1997|p=38}} but little is known about the Asian hybrid {{nowrap|''T.'' × ''komarovii''}}. One of its parents is ''T.&nbsp;camschatcense'' but the other parent is unknown.{{r|POWO:961664-1}}

The only named hybrid in North America is {{nowrap|''T.'' × ''crockerianum''}} whose [[type specimen]] was collected in [[Del Norte County, California]].{{r|IPNI:1015183-1}} As originally described, its parents are ''Trillium ovatum'' and ''Trillium rivale'', but the latter species is now a member of genus ''[[Pseudotrillium]]'', and so {{nowrap|''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.&nbsp;erectum'', ''T.&nbsp;flexipes'', and ''T.&nbsp;vaseyi'' produced solid, seemingly viable seed. Seeds of the cross between ''T.&nbsp;camschatcense'' and ''T.&nbsp;erectum'' flowered in 9 to 10&nbsp;years.{{sfnp|Case|Case|1997|pp=38,69}}

===Disease===
[[File:Trillium_grandiflorum_at_the_North_Walker_Woods1.jpg|thumb|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 [[phytoplasma]]s that alter the morphology of infected plants.{{r|Candeias 2021}} Symptoms of phytoplasma infection include abnormal green markings on the petals (floral [[virescence]]), extra leaves ([[phyllody]]), and other abnormal characteristics.{{r|Case 1994}} Infected populations occur throughout the species range but are prevalent in Ontario, Michigan, and New York.{{r|Gates 1917}}

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 microscope|electron microscopy]] to detect the presence of mycoplasma-like organisms (i.e., phytoplasmas) in ''T.&nbsp;grandiflorum'' with virescent petals. The means of transmission was not established but [[leafhopper]]s were suspected.{{r|Hooper et al. 1971}} {{As of|November 2021}}, the insect [[Disease vector|vector]] for ''Trillium'' greening disorder is unknown.

Phytoplasmas were positively identified in ''T.&nbsp;grandiflorum'' and ''T.&nbsp;erectum'' in Ontario in 2016. [[Phylogenetics|Phylogenetic analysis]] supported the grouping of the phytoplasmas isolated from infected plants as a related strain of '[[Candidatus Phytoplasma pruni|''Candidatus'' Phytoplasma pruni]]' (subgroup 16SrIII-F) with 99% sequence identity.{{r|Arocha-Rosete et al. 2016}} This subgroup of phytoplasmas is associated with various other diseases, including [[Milkweed yellows phytoplasma#Milkweed yellows|milkweed yellows]], ''Vaccinium'' [[witches' broom]], and potato purple top.{{r|Davis et al. 2013}}

==Conservation==
[[File:The Great White Trillium.JPG|thumb|right|''[[Trillium grandiflorum]]'' (great white trillium)]]

Picking parts off a trillium plant can kill it even if the rhizome is left undisturbed.<ref name=mich>{{cite web |last1=O'Connor |first1=R. P. |first2=M. R. |last2=Penskar |date=2004 |url=https://mnfi.anr.msu.edu/abstracts/botany/trillium_undulatum.pdf |title=Special plant abstract for ''Trillium undulatum'' (painted trillium) |publisher=Michigan Natural Features Inventory |location=Lansing, MI, USA }}</ref> 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]]<ref name=mich /> and [[Minnesota]]<ref>Wisconsin [http://law.justia.com/minnesota/codes/17/18h-s18.html 2005 Minnesota Code – 18H.18 — Conservation of Certain Wildflowers.] US Codes and Statutes: Minnesota.</ref> it is illegal to pick trilliums. In New York it is illegal to pick the [[Trillium erectum|red trillium]].<ref>{{cite journal |last=Nuffer |first=B. |url=http://www.dec.ny.gov/pubs/53538.html |title=Red Trillium |journal=New York State Conservationist |date=April 2009 |publisher=New York State Department of Environmental Conservation |access-date=23 May 2011 |archive-date=10 May 2011 |archive-url=https://web.archive.org/web/20110510082532/http://www.dec.ny.gov/pubs/53538.html }}</ref>

In 2009, the [[Ontario Trillium Protection Act]], 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.<ref>Legislative Assembly of Ontario [http://www.ontla.on.ca/web/bills/bills_detail.do?locale=en&BillID=2194&detailPage=bills_detail_the_bill An Act to amend the Floral Emblem Act.] {{Webarchive|url=https://web.archive.org/web/20170525104625/http://www.ontla.on.ca/web/bills/bills_detail.do?locale=en&BillID=2194&detailPage=bills_detail_the_bill |date=25 May 2017 }} ''Bill 184, Ontario Trillium Protection Act 2009''.</ref> The rare ''[[Trillium flexipes]]'' (drooping trillium) is also protected by law in Ontario, because of its decreasing Canadian population.<ref>{{Cite web |url=https://www.ontario.ca/page/drooping-trillium |title=Drooping trillium |date=17 July 2014 |website=Government of Ontario |language=en |access-date=22 September 2018 }}</ref>

High [[white-tailed deer]] population density has been shown to decrease or eliminate trillium in an area, particularly white trillium.<ref>{{Cite journal |last1=Rooney |first1=Thomas P. |last2=Gross |first2=Kevin |date=2003 |title=A Demographic Study of Deer Browsing Impacts on ''Trillium grandiflorum'' |journal=Plant Ecology |volume=168 |issue=2 |pages=267–277 |jstor=20146481 |doi=10.1023/A:1024486606698 |bibcode=2003PlEco.168..267R |s2cid=16769133 }}</ref> 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.<ref>{{Cite journal |last1=Koh |first1=Saewan |last2=Bazely |first2=Dawn R. |last3=Tanentzap |first3=Andrew J. |last4=Voigt |first4=Dennis R. |last5=Da Silva |first5=Eric |date=March 2010 |title=''Trillium grandiflorum'' height is an indicator of white-tailed deer density at local and regional scales |journal=Forest Ecology and Management |volume=259 |issue=8 |pages=1472–1479 |doi=10.1016/j.foreco.2010.01.021 |bibcode=2010ForEM.259.1472K |issn=0378-1127 }}</ref>

Some species are harvested from the wild to an unsustainable degree. This is particularly dire in the case of ''T.&nbsp;govanianum'', whose high selling price as a folk medicine has motivated harvesters to destroy swathes of ecologically sensitive Himalayan forests, causing mudslides.<ref>{{cite news |last1=Sharma |first1=Suresh |title=Nag Chhatri trade strips forests, upsets ecology |url=https://timesofindia.indiatimes.com/city/chandigarh/Nag-Chhatri-trade-strips-forests-upsets-ecology/articleshow/38983296.cms |access-date=17 September 2019 |work=Times of India |date=24 July 2014 }}</ref>

==Medicinal uses==

Several species contain [[sapogenin]]s. They have been used traditionally as [[Uterotonic|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.<ref>Meyer, J. E. ''The Herbalist and Herb Doctor.'' Hammond, IN: Indiana Herb Gardens, 1918, p. 50.</ref>

==Culture==
[[File:Ottawacourthouse.jpg|thumb|Ontario trillium emblem on an Ottawa courthouse sign.]]

The white trillium (''[[Trillium grandiflorum]]'') serves as the [[List of Canadian provincial and territorial symbols|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.<ref>{{Cite web|url=https://www.netstate.com/states/symb/wildflowers/oh_large_white_trillium.htm|title=Ohio State Wildflower, Large White Trillium (Trillium grandiflorum), from NETSTATE.COM|website=www.netstate.com}}</ref> In light of their shared connection to the flower, the [[Major League Soccer]] teams in [[Toronto FC|Toronto]] and [[Columbus Crew SC|Columbus]] compete with each other for the [[Trillium Cup]].

[[Citizen science|Citizen scientists]] regularly report observations of ''Trillium'' species from around the world. ''T.&nbsp;grandiflorum'', [[Trillium erectum|''T.&nbsp;erectum'']], and [[Trillium ovatum|''T.&nbsp;ovatum'']] (in that order) are the most often observed ''Trillium'' species.<ref>{{cite web |title=Citizen science observations of ''Trillium'' species |url=https://www.inaturalist.org/observations?place_id=any&taxon_id=49465&view=species |publisher=[[iNaturalist]] |access-date=1 September 2019 }}</ref>

''Trillium'' is the [[literary magazine]] of [[Ramapo College|Ramapo College of New Jersey]], which features poetry, fiction, photography, and other visual arts created by Ramapo students.<ref>{{Cite web |url=https://www.ramapo.edu/trillium/ |title=Trillium |publisher=Ramapo College of New Jersey }}</ref>

In 1999, Michael Page established the use of the trillium flower as a symbol of [[bisexuality]].<ref>{{cite web |last1=Eidson |first1=Jessica |title=Plants That Can Symbolize LGBTQIA+ Pride |url=https://discoverandshare.org/2024/06/25/lgbtqiaplants/#:~:text=The%20trillium%20flower%20has%20symbolized,bisexual%20pride%20flag%20in%202001. |website=Discover + Share |date=June 25, 2024 |publisher=Missouri Botanical Garden}}</ref><ref>{{cite web |last1=Eyvanaki |first1=Ashley |title=Queer Objects: William Keble Martin Lily Illustration |url=https://outandabout.exeter.ac.uk/2020/10/29/queer-objects-william-keble-martin-lily-illustration/ |website=out and about |date=October 29, 2020 |publisher=University of Exeter |access-date=August 14, 2024}}</ref><ref>{{cite web |title=Bisexual Botany |url=https://www.lpzoo.org/bisexual-botany/#:~:text=Around%202001%2C%20the%20Mexican%20bisexual,Michigan%20lilies%20at%20Nature%20Boardwalk. |website=Lincoln Park Zoo | date=June 20, 2024 |access-date=August 14, 2024}}</ref> This was a [[pun]], as scientists had used the term "bisexual" to refer to the flower because such flowers have [[hermaphrodite|both male and female reproductive organs]].<ref>{{cite web |last1=Eidson |first1=Jessica |title=Plants That Can Symbolize LGBTQIA+ Pride |url=https://discoverandshare.org/2024/06/25/lgbtqiaplants/#:~:text=The%20trillium%20flower%20has%20symbolized,bisexual%20pride%20flag%20in%202001. |website=DISCOVER + SHARE |date=25 June 2024 |publisher=Missouri Botanical Garden}}</ref>

==Gallery==

<gallery>
File:Nodding trillium flower -SC woodlot- 3.JPG|Nodding trillium (''[[Trillium cernuum]]'')
File:Trillium petiolatum- Washington.jpg|Idaho trillium (''[[Trillium petiolatum]]'')
File:Trillium with the leaves.jpg|White trillium (''[[Trillium grandiflorum]]'')
File:Red trillium (42136561721).jpg|Red trillium (''[[Trillium erectum]]'')
File:Trillium ovatum 1290.JPG|Pacific trillium (''[[Trillium ovatum]]'')
File:TrilliumRecurvatum.jpg|Prairie trillium (''[[Trillium recurvatum]]'')
File:Trillium reliquum.jpg|Relict trillium (''[[Trillium reliquum]])'' an [[endangered species]]
File:Painted Trillium.jpg|Painted trillium (''[[Trillium undulatum]]'')
</gallery>

==References==

{{Reflist|30em|refs=

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<ref name="Davis et al. 2013">{{cite journal |last1=Davis |first1=R.E. |last2=Zhao |first2=Y. |last3=Dally |first3=E.L. |last4=Lee |first4=I.M. |last5=Jomantiene |first5=R. |last6=Douglas |first6=S.M. |title='''Candidatus'' Phytoplasma pruni', a novel taxon associated with X-disease of stone fruits, ''Prunus'' spp.: multilocus characterization based on 16S rRNA, secY, and ribosomal protein genes |journal=Int J Syst Evol Microbiol |date=2013 |volume=63 |issue=Pt 2 |pages=766–776 |doi=10.1099/ijs.0.041202-0 |pmid=22798643 |bibcode=2013IJSEM..63..766D }}</ref>

<ref name="Farmer 2006">{{cite journal |last1=Farmer |first1=Susan B. |title=Phylogenetic Analyses and Biogeography of Trilliaceae |journal=Aliso: A Journal of Systematic and Evolutionary Botany |date=2006 |volume=22 |issue=1 |pages=579–592 |doi=10.5642/aliso.20062201.45 |doi-access=free }}</ref>

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<ref name="FNA:312202">{{eFloras |1 |312202 |Trillium subg. Trillium |volume=26 |last=Case |first=Frederick W. Jr. }}</ref>

<ref name="FNA:312201">{{eFloras |1 |312201 |Trillium subg. Phyllantherum |volume=26 |last=Case |first=Frederick W. Jr. }}</ref>

<ref name="FOC 200027979">{{eFloras |2 |200027979 |Trillium govanianum |volume=24 |last1=Liang |first1=Songyun |last2=Soukup |first2=Victor G. }}</ref>

<ref name="FOP 133668">{{eFloras |5 |133668 |Trillium }}</ref>

<ref name="Gates 1917">{{cite journal |last1=Gates |first1=R.R. |title=A systematic study of the North American genus ''Trillium'', its variability, and its relation to ''Paris'' and ''Medeola'' |journal=Annals of the Missouri Botanical Garden |date=February 1917 |volume=4 |issue=1 |pages=43–92 |doi=10.2307/2990062 |jstor=2990062 |bibcode=1917AnMBG...4...43G |url=https://www.biodiversitylibrary.org/item/54259#page/51/mode/1up |access-date=28 October 2021 |archive-date=28 October 2021 |archive-url=https://web.archive.org/web/20211028150443/https://www.biodiversitylibrary.org/item/54259#page/51/mode/1up |url-status=live }}</ref>

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<ref name="IPNI:1015183-1">{{IPNI |id=1015183-1 |taxon=Trillium × crockerianum |authority=Halda |access-date=2 December 2021 }}</ref>

<ref name="IPNI:24183-1">{{IPNI |id=24183-1 |taxon=''Delostylis'' |authority={{small|Raf.}} |access-date=25 March 2023 }}</ref>

<ref name="IPNI:60464604-2">{{IPNI |id=60464604-2 |taxon=''Trillium'' subgen.&nbsp;''Delostylis'' |authority={{small|(Raf.) Raf.}} |access-date=25 March 2023 }}</ref>

<ref name="IPNI:60464242-2">{{IPNI |id=60464242-2 |taxon=''Trillium'' subgen.&nbsp;''Phyllantherum'' |authority={{small|Raf.}} |access-date=25 March 2023 }}</ref>

<ref name="IPNI:60464602-2">{{IPNI |id=60464602-2 |taxon=''Trillium'' subgen.&nbsp;''Sessilia'' |authority={{small|Raf.}} |access-date=25 March 2023 }}</ref>

<ref name="IPNI:77301132-1">{{IPNI |id=77301132-1 |taxon=''Trillium'' subgen.&nbsp;''Callipetalon'' |authority={{small|Lampley & E.E.Schill.}} |access-date=25 March 2023 }}</ref>

<ref name="Kunth 1850">{{cite journal |last1=Kunth |first1=Karl Sigismund |title=''Trillidium'' |journal=Enumeratio Plantarum Omnium Hucusque Cognitarum, Secundum Familias Naturales Disposita, Adjectis Characteribus, Differentiis et Synonymis |date=1850 |volume=5 |page=120 |url=https://www.biodiversitylibrary.org/page/7425851#page/130/mode/1up |access-date=30 November 2021 |location=Stutgardiae et Tubingae [Stuttgart and Tübingen] }}</ref>

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<ref name="Patrick 2007">{{cite journal |last1=Patrick |first1=Tom |year=2007 |title=Trilliums of Georgia |journal=Tipularia |volume=22 |pages=3–22 }}</ref>

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<ref name="POWO:258353-2">{{cite POWO |id=258353-2 |title=''Trillium parviflorum'' |access-date=17 February 2023 }}</ref>

<ref name="POWO:542551-1">{{cite POWO |id=542551-1 |title=''Trillium govanianum'' |access-date=17 February 2023 }}</ref>

<ref name="POWO:542515-1">{{cite POWO |id=542515-1 |title=''Trillium apetalon'' |access-date=17 February 2023 }}</ref>

<ref name="POWO:542620-1">{{cite POWO |id=542620-1 |title=''Trillium'' × ''yezoense'' |access-date=17 February 2023 }}</ref>

<ref name="POWO:542611-1">{{cite POWO |id=542611-1 |title=''Trillium tschonoskii'' |access-date=17 February 2023 }}</ref>

<ref name="POWO:937303-1">{{cite POWO |id=937303-1 |title=''Trillium taiwanense'' |access-date=17 February 2023 }}</ref>

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<ref name="POWO:542604-1">{{cite POWO |id=542604-1 |title=''Trillium smallii'' |access-date=17 February 2023 }}</ref>

<ref name="POWO:989638-1">{{cite POWO |id=989638-1 |title=''Trillium channellii'' |access-date=17 February 2023 }}</ref>

<ref name="POWO:542554-1">{{cite POWO |id=542554-1 |title=''Trillium'' × ''hagae'' |access-date=17 February 2023 }}</ref>

<ref name="POWO:542571-1">{{cite POWO |id=542571-1 |title=''Trillium'' × ''miyabeanum'' |access-date=17 February 2023 }}</ref>

<ref name="POWO:1015183-1">{{cite POWO |id=1015183-1 |title=''Trillium'' × ''crockerianum'' |access-date=23 March 2023 }}</ref>

<ref name="Rafinesque 1830">{{cite book |last1=Rafinesque |first1=C. S. |title=Medical Flora; or Manual of the Medical Botany of the United States of North America |volume=2 |date=1830 |location=Philadelphia |page=97 |url=https://www.biodiversitylibrary.org/page/46930269#page/175/mode/1up |access-date=14 February 2022 }}</ref>

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<ref name="Zettler et al. 2001">{{Cite journal |last1=Zettler |first1=Jennifer A. |last2=Spira |first2=Timothy P. |last3=Allen |first3=Craig R. |date=2001 |title=Yellow Jackets (Vespula spp.) Disperse Trillium (spp.) Seeds in Eastern North America |journal=The American Midland Naturalist |volume=146 |issue=2 |pages=444–446 |doi=10.1674/0003-0031(2001)146[0444:YJVSDT]2.0.CO;2 |jstor=3082926 |s2cid=37149406 |issn=0003-0031 |url=https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1149&context=ncfwrustaff |url-access=subscription }}</ref>

}}

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* {{cite journal |last1=Lampley |first1=Jayne A. |last2=Gereau |first2=Roy |last3=Floden |first3=Aaron |last4=Schilling |first4=Edward E. |title=A revised subgeneric classification of ''Trillium'' (Parideae, Melanthiaceae) |journal=Phytotaxa |date=5 July 2022 |volume=552 |issue=5 |pages=278–286 |doi=10.11646/phytotaxa.552.5.1 |s2cid=250368253 |doi-access=free |bibcode=2022Phytx.552..278L}}
* {{cite book |last1=Meredith |first1=Clayton |last2=Frances |first2=Anne |last3=Highland |first3=Amy |last4=Oliver |first4=Leah |last5=Floden |first5=Aaron |last6=Gaddy |first6=L.L. |last7=Knapp |first7=Wesley |last8=Leaman |first8=Danna |last9=Leopold |first9=Susan |last10=Littlefield |first10=Tara |last11=Raguso |first11=Robert |last12=Schilling |first12=Edward |last13=Schotz |first13=Alfred |last14=Walker |first14=Anna |last15=Wayman |first15=Kjirsten |title=The Conservation Status of ''Trillium'' in North America |date=2022 |publisher=Mt. Cuba Center, and New Mexico BioPark Society |location=Hockessin, DE and Albuquerque, NM |isbn=979-8-9850471-0-3 |url=https://issuu.com/mtcuba/docs/the_conservation_status_of_trillium_in_north_ameri?e=43224013/92008195 |access-date=19 March 2023}}
* {{Citation |last=Patrick |first=Thomas S. |title=The trilliums of eastern North America |publisher=University of Tennessee |publication-place=Knoxville |date=August 1986 |pages=1–7 |type=mimeographed handout |url=https://drive.google.com/file/d/1yxd3HnsibazS5eFxT1p8eXf_pZPSQUxy/view |access-date=30 March 2023}}
* {{cite journal |last1=Spaulding |first1=Daniel D. |last2=Kartesz |first2=John T. |last3=Horne |first3=Howard E. |last4=Finzel |first4=Brian J. |last5=England |first5=J. Kevin |title=Flora of Northern Alabama, part 5: Liliaceous Families |journal=Phytoneuron |date=2021 |volume=2021-30 |pages=1–262 |url=https://www.phytoneuron.net/wp-content/uploads/2021/08/30PhytoN-AlabamaFlora5.pdf |access-date=9 March 2023 |issn=2153-733X}}
* {{cite journal |last1=Wayman |first1=Kjirsten A. |last2=Reilly |first2=Matthew J. |last3=Petlewski |first3=Alaina R. |title=Taxonomic insights from floral scents of western North American sessile-flowered ''Trillium'' |journal=American Journal of Botany |date=December 2023 |volume=110 |issue=12 |article-number=e16255 |doi=10.1002/ajb2.16255 |pmid=37938811 |bibcode=2023AmJB..11016255W}}
* {{cite web |last1=Weakley |first1=Alan S. |title=Flora of the southeastern United States |publisher=University of North Carolina Herbarium, North Carolina Botanical Garden |date=2020 |url-access=registration |url=https://ncbg.unc.edu/research/unc-herbarium/flora-request/}}

==External links==

{{Commons category}}
* [https://web.archive.org/web/20070518101802/http://utc.usu.edu/keys/trillium/Trillium.html Interactive Identification Key] ([[Java (programming language)|Java]])
* [https://archive.today/20070518101917/http://utc.usu.edu/factsheets/trillium/trillium.htm Utah Agricultural Experiment Station — Fact Sheets]
* McKelvie, D. [https://archive.today/20130415150519/http://www.ont-woodlot-assoc.org/sw_woodlandplants.html Woodland Plants: The Trillium.] Ontario Woodlot Association.
* [http://bison.usgs.ornl.gov/api/scientificName/Trillium/arguments/itis Biodiversity Information Serving Our Nation (BISON) occurrence data and maps for ''Trillium'']{{Dead link|date=October 2025 |bot=InternetArchiveBot }}
* {{cite journal |last1=Friesner |first1=Ray C. |title=The genus ''Trillium'' in Indiana |journal=Butler University Botanical Studies |series=Butler University Botanical Studies: Vol. 1, Article 4 |url=https://digitalcommons.butler.edu/botanical/vol1/iss1/4 |access-date=28 September 2021 |date=1929 |volume=1 |issue=1}}
* {{cite web |title=About Trilliums |url=https://www.fs.fed.us/wildflowers/beauty/trilliums/about.shtml |publisher=U.S. Forest Service |access-date=3 November 2021}}
* {{cite web |title=Ten Things to Know about Trilliums |url=https://nativeplantherald.prairienursery.com/2015/02/ten-things-to-know-about-trilliums/ |website=The Native Plant Herald |access-date=21 January 2022 }}{{Dead link|date=April 2026 |bot=InternetArchiveBot }}
* {{cite journal |last1=Ohara |first1=Masashi |last2=Kawano |first2=Shoichi |title=Life History Studies on the Genus ''Trillium'' (Liliaceae) IV. Stage Class Structures and Spatial Distribution of Four Japanese Species |journal=Plant Species Biology |date=1986 |volume=1 |issue=2 |pages=147–161 |doi=10.1111/j.1442-1984.1986.tb00023.x |bibcode=1986PSBio...1..147O |url=http://www.shieldsgardens.com/Science/PDFs/Ohara_Kawano_Plant_Species_Biology1986v1pp147-161.pdf |access-date=1 February 2022}}
* {{cite web |title=Trillium and the Trillium Family (Trilliaceae) |url=https://www.goldsword.com/sfarmer/Trillium/ |publisher=Susan B. Farmer |access-date=6 February 2022}}
* {{cite web |last1=Patrick |first1=Tom |title=Georgia Trilliums: An Appreciation |url=https://www.yumpu.com/en/document/view/11488581/gnps-2010-symposium-handout-tom-patrick |access-date=10 February 2022 |date=2010}}
* {{cite web |title=Feeling Antsy |url=https://roadsendnaturalist.com/tag/elaiosome/ |website=Roads End Naturalist |access-date=2 July 2022 |date=23 July 2019}}
* {{cite web |title=Trilliums! |url=http://www.scottranger.com/trilliums.html |website=Scott Ranger's Nature Notes |access-date=7 March 2023}}
* {{cite web |title=''Trillium'' |url=https://michiganflora.net/genus/Trillium |website=Michigan Flora Online |publisher=University of Michigan |access-date=7 March 2023}}
* {{cite journal |last1=Peattie |first1=Donald Culross |title=''Trillium'' in North Carolina and South Carolina: A Critical Systematic Reconnaissance |url=https://dc.lib.unc.edu/cdm/ref/collection/jncas/id/1410 |journal=Journal of the Elisha Mitchell Scientific Society |date=1927 |volume=42 |issue=3–4 |pages=193–206}}

{{Taxonbar|from=Q475629}}

[[Category:Trillium| ]]
[[Category:Melanthiaceae genera]]
[[Category:Flora of Canada]]
[[Category:Flora of the United States]]
[[Category:Botanical taxa named by Carl Linnaeus]]