The Erectum Group
Until recently, the Erectum Group was an ill-defined group of taxa in genus Trillium but the taxonomy of the genus has improved significantly thanks to a line of research culminating in a paper published in 2022. According to that paper, [Lampley et al. 2022] the Erectum Group is synonymous with Trillium subgenus Trillium, one of four subgenera in the genus. In the iNaturalist taxonomy, subgenus Trillium consists of the following taxa:
| Asia | North America |
|---|---|
| Trillium apetalon | Trillium cernuum (Nodding Trillium) |
| Trillium camschatcense (Kamchatka Trillium) | Trillium erectum (Red Trillium) |
| Trillium channellii | Trillium flexipes (Drooping Trillium) |
| Trillium × hagae | Trillium hibbersonii (Hibberson's Trillium) |
| Trillium × komarovii | Trillium rugelii (Southern Nodding Wakerobin) |
| Trillium × miyabeanum | Trillium simile (Jewelled Wakerobin) |
| Trillium smallii (Small's Trillium) | Trillium sulcatum (Southern Red Trillium) |
| Trillium tschonoskii (Mountain Woods Trillium) | Trillium vaseyi (Vasey's Trillium) |
| Trillium × yezoense | |
Subgenus Trillium is typified by T. erectum, hence the name Erectum Group.
Distribution
Trillium subgenus Trillium is widely distributed in North America and Asia. In North America, members of the subgenus are found across Canada from Saskatchewan to Newfoundland, ranging southward to the southern Appalachian Mountains in the southeastern United States.
Subgenus Trillium in Canada:
- British Columbia: T. hibbersonii (a geographic outlier)
- Manitoba: T. cernuum
- New Brunswick: T. cernuum, T. erectum
- Newfoundland: T. cernuum
- Nova Scotia: T. cernuum, T. erectum
- Ontario: T. cernuum, T. erectum, T. flexipes (S1)
- Prince Edward Island: T. cernuum
- Quebec: T. cernuum, T. erectum
- Saskatchewan: T. cernuum
Subgenus Trillium in the United States:
- Alabama: T. flexipes, T. sulcatum (S1), T. vaseyi (S1)
- Arkansas: T. flexipes (S1)
- Connecticut: T. cernuum, T. erectum
- Delaware: T. cernuum (S2), T. erectum (S1), T. flexipes
- Georgia: T. erectum, T. flexipes (S1), T. rugelii, T. simile (S2), T. sulcatum (S2), T. vaseyi
- Illinois: T. cernuum (S1), T. erectum (S1), T. flexipes
- Indiana: T. cernuum, T. erectum, T. flexipes
- Iowa: T. cernuum, T. flexipes
- Kentucky: T. erectum, T. flexipes, T. sulcatum
- Maine: T. cernuum, T. erectum
- Maryland: T. cernuum, T. erectum, T. flexipes (S1)
- Massachusetts: T. cernuum, T. erectum
- Michigan: T. cernuum, T. erectum, T. flexipes
- Minnesota: T. cernuum, T. flexipes
- Missouri: T. flexipes
- New Hampshire: T. cernuum, T. erectum
- New Jersey: T. cernuum, T. erectum
- New York: T. cernuum, T. erectum, T. flexipes (S1)
- North Carolina: T. erectum, T. flexipes (S1), T. rugelii, T. simile (S2), T. sulcatum, T. vaseyi
- North Dakota: T. cernuum
- Ohio: T. cernuum (SX), T. erectum, T. flexipes
- Pennsylvania: T. cernuum (S2), T. erectum, T. flexipes (S2)
- Rhode Island: T. cernuum, T. erectum (S1)
- South Carolina: T. erectum, T. rugelii (S2), T. simile (S1S2), T. vaseyi
- South Dakota: T. cernuum (S2), T. flexipes
- Tennessee: T. erectum, T. flexipes, T. rugelii (S2), T. simile, T. sulcatum, T. vaseyi
- Vermont: T. cernuum, T. erectum
- Virginia: T. cernuum (S2), T. erectum, T. flexipes (SH), T. sulcatum
- West Virginia: T. cernuum (S1), T. erectum, T. flexipes (S2), T. sulcatum
- Wisconsin: T. cernuum, T. flexipes
In Asia, the majority of observations have been made in eastern Asia.
Subgenus Trillium in Asia:
- Bhutan: T. tschonoskii
- China: T. camschatcense, T. tschonoskii
- India: T. tschonoskii
- Japan: T. apetalon, T. camschatcense, T. channellii, T. × hagae, T. × komarovii, T. × miyabeanum, T. smallii, T. tschonoskii, T. × yezoense
- Korea: T. camschatcense, T. tschonoskii
- Kuril Islands: T. apetalon, T. camschatcense, T. tschonoskii
- Myanmar: T. tschonoskii
- Russia: T. apetalon, T. camschatcense, T. × hagae, T. × komarovii, T. smallii, T. tschonoskii
- Taiwan: T. tschonoskii
Based on iNaturalist observations, T. erectum is the most observed species of the subgenus (by far). The center of diversity for the subgenus occurs in the southern Appalachians.
