Editing Trillium (section)

==Subdivisions==
All names used in this section are taken from the [[International Plant Names Index]].<ref>{{IPNI |search=Trillium |accessdate=2019-10-08}}</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}}</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}}</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 }}</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}}</ref> – E Taiwan
* ''[[Trillium tschonoskii]]'' {{small|Maxim.}}{{r|POWO:542611-1}}<ref name="FOC 200027981">{{eFloras |2 |200027981 |Trillium tschonoskii |volume=24}}</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>{{ThePlantList |id=kew-290601 |taxon=Trillium parviflorum |authority=V.G.Soukup |accessdate=10 August 2019}}</ref><ref name="FNA 242102003">{{eFloras |1 |242102003 |Trillium parviflorum |volume=26 |last=Case Jr. |first=Frederick W. |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}}.<ref>{{WCSP |290601 |''Trillium parviflorum''}}</ref>{{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 Jr. |first=Frederick W. |access-date=July 16, 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}}