Species Profile

Tweedy's Lewisia

Scientific Name: Lewisiopsis tweedyi
Taxonomy Group: Vascular Plants
Range: British Columbia
Last COSEWIC Assessment: November 2013
Last COSEWIC Designation: Endangered
SARA Status: No schedule, No Status

Individuals of this species may be protected under Schedule 1 under another name; for more information see Schedule 1, the A-Z Species List, or if applicable, the Related Species table below.

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Quick Links: | Description | Habitat | Biology | Threats | Protection | National Recovery Program | Documents

Image of Tweedy's Lewisia


Tweedy’s Lewisia occurs from south-central British Columbia south through the Wenatchee Mountains into central Washington State. In Canada, Tweedy’s Lewisia is known from two sites in the Cascade Mountain Ranges, in E.C. Manning Provincial Park. (Updated 2017/08/04)


Distribution and Population

Tweedy’s Lewisia occurs from south-central British Columbia south through the Wenatchee Mountains into central Washington State. In Canada, Tweedy’s Lewisia is known from two sites in the Cascade Mountain Ranges, in E.C. Manning Provincial Park. (Updated 2017/08/04)



In Canada, Tweedy’s Lewisia occurs on dry south-facing slopes, in subalpine areas within the Moist Warm subzone of the Engelmann Spruce – Subalpine Fir biogeoclimatic zone. This subzone experiences long, cold winters featuring heavy snowfall, and short, cool summers. Substantial snowpacks may persist into June. The plants occur in stable, fractured rock outcrops where needle litter accumulates; in areas with a light canopy of mature Douglas-fir, or no trees. Most of the clumps occur on southeast-facing ledges and crevices while few were found on level surfaces. The shrub and herb layers are sparse and interspecific interactions between Tweedy’s Lewisia and other low-growing species are probably weak. The habitat in the vicinity of the Site 1 subpopulation is not obviously vulnerable to any major disturbances. The habitat surrounding the Site 2 subpopulation has been significantly altered by road building and subsequent road re-alignment but there is no ongoing road building. (Updated 2017/08/04)



The Canadian population flowers between mid-June and late July. Bees and syrphid flies made up the majority of observed daytime flower visitors but it is not certain that they are the main pollinators. Tweedy's Lewisia is self-fertile and there is little difference in seed set regardless of whether plants were self-fertilized, fertilized by other plants of the same subpopulation, or fertilized by plants from distant subpopulations. The flower scapes of Tweedy`s Lewisia tend to reflex if several seeds are produced, which increases the likelihood that seeds will fall close to the parent. The seeds, which have a sweet honey scent, are often dispersed by ants. Seeds germinate in the autumn or spring and existing plants break shoot dormancy as the snow is melting. Seed viability in Tweedy's Lewisia varies considerably. While germination and growth may begin soon after the seeds are sown, deposited seeds remain viable and may germinate episodically for up to 18 months. Tweedy's Lewisia is adapted to summer drought but is not adapted to winter rains. Tweedy's Lewisia may be grazed by American Pika, Mule Deer, and Elk. The degree of herbivory tends to be highest among large subpopulations of Tweedy's Lewisia. (Updated 2017/08/04)



The distribution of Tweedy's Lewisia in Canada is strictly limited by the relatively small area of suitable habitat within its narrow extent of occurrence. Existing subpopulations are threatened by plant collecting and more severe summer droughts as an apparent result of climate change. (Updated 2017/08/04)



Federal Protection

Provincial and Territorial Protection

To know if this species is protected by provincial or territorial laws, consult the provinces' and territories' websites.



PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.

6 record(s) found.

COSEWIC Status Reports

  • COSEWIC assessment and status report on the Tweedy’s Lewisia Lewisiopsis tweedyi in Canada (2014)

    Tweedy’s Lewisia is a clump-forming perennial herb arising from a thick, fleshy, reddish taproot. The evergreen, fleshy leaves form a basal cluster, from which arise multiple stems, each bearing 2-5 showy salmon-coloured, yellowish-pink or white flowers. Tweedy’s Lewisia is a distinctive showy species that has long been grown as an ornamental but has a reputation for being difficult to keep alive and therefore of commercial interest only to alpine garden specialists.

Response Statements

  • Response Statement - Tweedy's Lewisia (2015)

    This showy perennial plant is known only from Washington and British Columbia. It exists in Canada as two small subpopulations and has undergone a decline of up to 30% in recent years, possibly due to plant collecting. The small population size and potential impact from changes in moisture regimes due to climate change place the species at on-going risk.


  • Order Acknowledging Receipt of the Assessments Done Pursuant to Subsection 23(1) of the Act (2017)

    His Excellency the Governor General in Council, on the recommendation of the Minister of the Environment, acknowledges receipt, on the making of this Order, of the assessments done pursuant to subsection 23(1) of the Species at Risk Act by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) with respect to the species set out in the annexed schedule.
  • Order Amending Schedule 1 to the Species at Risk Act (2017)

    Biodiversity is rapidly declining worldwide as species become extinct. Today’s extinction rate is estimated to be between 1 000 and 10 000 times higher than the natural rate. Biodiversity is positively related to ecosystem productivity, health and resiliency (i.e. the ability of an ecosystem to respond to changes or disturbances). Given the interdependency of species, a loss of biodiversity can lead to decreases in ecosystem function and services (e.g. natural processes such as pest control, pollination, coastal wave attenuation, temperature regulation and carbon fixing). These services are important to the health of Canadians, and also have important ties to Canada’s economy. Small changes within an ecosystem resulting in the loss of individuals and species can therefore result in adverse, irreversible and broad-ranging effects.

COSEWIC Annual Reports

  • COSEWIC Annual Report - 2013-2014 (2014)

    Under Canada’s Species at Risk Act (SARA), the foremost function of COSEWIC is to "assess the status of each wildlife species considered by COSEWIC to be at risk and, as part of the assessment, identify existing and potential threats to the species". COSEWIC held two Wildlife Species Assessment Meetings in this reporting year (October, 2013 to September, 2014) from November 24 to November 29, 2013 and from April 27 to May 2, 2014. During the current reporting period, COSEWIC assessed the status or reviewed the classification of 56 wildlife species. The wildlife species assessment results for the 2012-2013 reporting period include the following: Extinct: 0 Extirpated: 0 Endangered: 23 Threatened: 12 Special Concern: 20 Data Deficient: 0 Not at Risk: 1 Total: 56 Of the 56 wildlife species examined, COSEWIC reviewed the classification of 40 that had been previously assessed. The review of classification for 25 of those wildlife species resulted in a confirmation of the same status as the previous assessment.

Consultation Documents

  • Consultation on Amending the List of Species under the Species at Risk Act : Terrestrial Species - January 2015 (2015)

    The Government of Canada is committed to preventing the disappearance of wildlife species at risk from our lands. As part of its strategy for realizing that commitment, on June 5, 2003, the Government of Canada proclaimed the Species at Risk Act (SARA). Attached to the Act is Schedule 1, the list of the species provided for under SARA, also called the List of Wildlife Species at Risk. Extirpated, Endangered and Threatened species on Schedule 1 benefit from the protection of prohibitions and recovery planning requirements under SARA. Special Concern species benefit from its management planning requirements. Schedule 1 has grown from the original 233 to 521 wildlife species at risk. Please submit your comments byApril 15, 2015, for terrestrial species undergoing normal consultationsand byOctober 15, 2015, for terrestrial species undergoing extended consultations.For a description of the consultation paths these species will undergo, please see:Species at Risk Public Registry website