Virginia Goat’s Rue Evaluation
This document describes the Committee on the Status of Species at Risk in Ontario’s evaluation of Virginia goat’s rue. This evaluation determines whether the species will receive protection under the Endangered Species Act.
Committee on the Status of Species at Risk in Ontario (COSSARO)
Assessed November 2009 by COSSARO as Endangered
Part 1: COSSARO Candidate Species at Risk evaluation form - November 2009
Virginia Goat’s-rue (Tephrosia virginiana)
Current designations:
GRANK – G5 – Secure
NRANK Canada – N1 – Critically imperiled
COSEWIC – END (May 2000)
SARA – END (June 2003)
General Status Canada – At Risk
ESA 2007 – END
SRANK – S1
General Status Ontario – At Risk
Distribution and status outside Ontario:
This species ranges from Minnesota to Texas in the west and from New Hampshire to Florida in the east. It is limited by its requirement for non-calcareous soils and is therefore generally absent from heavily glaciated areas with glacial till (Wood, 1949).
Eligibility criteria
Native status
✔ Yes. There is no evidence to suggest that this species is not native to Ontario.
Taxonomic distinctness
✔ Yes. The species is recognized taxonomically as a widespread species without distinct morphological and geographical variation (Wood, 1949). It is the only member of the genus in Ontario.
Designatable units
There is a single DU in Ontario and Canada. The species occurs in a very limited area in Norfolk County, Ontario and is restricted to the Mixedwood Plains Ecoregion.
Priority-setting criteria
Recent arrival
✔ No. There is no evidence that suggests this species is a recent arrival in Ontario, since it was first collected in the province in 1885.
Non-resident
✔ No.
Primary criteria (rarity and declines)
1. Global rank
✔ Not in any category. The global rank is G5.
2. Global decline
✔ Not in any category. There is no evidence for a global decline.
3. Northeastern North America ranks
✔ Not in any category. The species is ranked as S1, S2, SH or SX in 3 of the 20 northeastern North American jurisdictions where it occurs (S1 in Ontario and Rhode Island and SH in New Hampshire).
4. Northeastern North America decline
✔ Not in any category. There is no evidence of a decline of more than 30% in northeastern North America.
5. Ontario occurrences
✔ END. There are only 2 extant occurrences of the species in Ontario.
6. Ontario decline
✔ THR. One of 3 Ontario populations has been lost since 1991, which is probably within 3 generations since generation time is "several years".
7. Ontario’s conservation responsibility
✔ Not in any category. Ontario contains <1% of the global range.
Secondary criteria (threats and vulnerability)
1. Population sustainability
✔ Not in any category. There is no substantial evidence for any reproductive or recruitment failure in Ontario populations.
2. Lack of regulatory protection for exploited wild populations
✔ Not in any category. There is no known exploitation of the species in Ontario.
3. Direct threats
END. There is a risk of erosion that is threatening one population, which is on a sand dune next to a road cut. Habitat decline through shading, trampling (most by illegal ATV activity) and invasion by exotic species continues at the other site. The species has already been extirpated by shading at one site.
4. Specialized life history or habitat-use characteristics
✔ END. The species has very specific habitat requirements and is restricted in Ontario to provincially rare savannah and prairie habitats (S1 community types) on acidic sand.
COSSARO criteria met (primary/secondary)
Endangered – [1/2]
Threatened – [1/0]
Special concern – [0/0]
Summary
Virginia Goat’s-rue (Tephrosia virginiana) is a perennial herb that occurs in Ontario only in provincially rare tallgrass prairie and savannah habitats on the acidic sand of the Norfolk Sand Plain. There are two extant sites in Ontario and one site that has been extirpated since 1991. One extant site is small with about 100 individuals. Direct threats to the species include loss of habitat and habitat degradation as a result of erosion, encroachment by woody species, trampling from ATVs and invasion by exotic species. It has been listed as Endangered in Canada since 2000.
Information sources
COSEWIC. 2009. COSEWIC status report on Virginia Goat’s-rue, Tephrosia virginiana. 2-month Interim Report. 29 pp.
NatureServe Explorer. 2009. An Online Encyclopedia of Life. Tephrosia virginiana. Accessed October 2009. Data on website updated as of 2 February 2009.
Wildspecies. 2009. The general status of species in Canada. Web site: http://www.wildspecies.ca/wildspecies2005/index.cfm?lang=e [accessed October 2009] [link no longer active].
Wood, C. E., Jr. 1949. The American barbistyled species of Tephrosia (Leguminosae). Contributions from the Gray Herbarium of Harvard University-No.CLXX. Rhodora 51: 193-231, 233-302, 305-364, 369-384.
Appendix 1:
Northeastern North America rank, status and decline
| CT | SNR |
| DE | S4 |
| IL | SNR |
| IN | SNR |
| IA | S3 |
| KY | S5 |
| LB | Not present |
| MA | SNR |
| MB | Not present |
| MD | SNR |
| ME | Not present |
| MI | SNR |
| MN | S3 |
| NB | Not present |
| NF | Not present |
| NH | SH |
| NJ | S4 |
| NS | Not present |
| NY | S4S5 |
| OH | SNR |
| ON | S1 |
| PA | SNR |
| PE | Not present |
| QC | Not present |
| RI | S1 |
| VA | S5 |
| VT | Not present |
| WI | SNR |
| WV | S5 |
Occurs as a native species in 20 of 29 northeastern jurisdictions = 69%
SRANK or equivalent information available for 11 of 20 jurisdictions = 55%
S1, S2, SH, or SX in 3 of 20 = 15%
Part 2: Ontario evaluation using COSEWIC criteria
Regional (Ontario) COSEWIC criteria assessment
Criterion A – declining population
No. The extent of decline in the number of individuals is unknown.
Criterion B – Small distribution and decline or fluctuation
END B1,2 (a),(b) i, ii, iii, iv. EO is <<5,000 km2; IAO <<500 km2. There are only 2 locations and continuing decline is observed and projected in;
- extent of occurrence;
- area of occupancy;
- quality of habitat; and
- number of populations.
Criterion C – Small population size and decline
END C2a(ii). There is continuing loss observed and projected for the total population numbering <2500 plants with one population having >95% of all individuals (COSEWIC, 2009).
Criterion D – Very small or restricted
THR D2. The area of occupancy is 20 km2 and there are only 2 populations. A stochastic event such as a widespread forest fire could eliminate most of the individuals.
Criterion E – Quantitative analysis
No. No PVA available.
Rescue effect
No. Rescue is unlikely because of the short distance dispersal of the species, the limited habitat available, the distance to the nearest populations and the intervening unsuitable habitat.