Bolander’s quillwort (Isoetes bolanderi) COSEWIC assessment and status report: chapter 2

Species Information

Bolander’s quillwort (Isoetes bolanderi) is a small, perennial aquatic plant classified as a fern-ally (pteridophyte); it has pale green, simple quill-like leaves arising from a corm embedded in the lake bottom.

 

Distribution

Isoetes bolanderi is endemic to the Rocky Mountains and the Coast, Cascade and Sierra Nevada mountains of western North America, extending from southwestern Alberta, southward to California, northern Arizona and New Mexico. It was first discovered in Canada in 1946 at Carthew Lakes, Waterton Lakes National Park, Alberta. This population has not been seen again, despite several recent searches. In 1953, a substantial population was discovered in Summit Lake, also in Waterton Lakes National Park. Currently, the entire Canadian population of Isoetes bolanderi is confined to the Summit Lake location, a single, small (2 ha), high-elevation lake. Consequently, both the Extent of Occurrence and Area of Occupancy for this species are 2 ha.

 

Habitat

Isoetes bolanderi grows in upper subalpine to alpine ponds and small lakes with clear, oligotrophic water supporting little or no associated vegetation within Isoetes stands. The Summit Lake population occupies a relatively stable situation. Physical impact by large ungulates has been noted but these appear to be localized events. It is not known if habitat change was involved in the extirpation of the Carthew Lakes population. The status and trend of Isoetes bolanderi habitat in the USA is unknown.The existing known location of Isoetes bolanderi in Canada is entirely within Waterton Lakes National Park and the species is protected by the Canada National Parks Act and Regulations.

 

Biology

The species grows in almost pure stands in circumneutral to slightly basic, silty sand substrate and extends across virtually all of the bottom of Summit Lake. It produces large quantities of viable spores and appears to be reproducing successfully within the lake. No vegetative reproduction is known for this species.

 

Population Sizes and Trends

In 2002 and 2003, 24 potentially suitable lakes were surveyed in southwestern Alberta and adjacent British Columbia but no additional populations were found. A detailed population survey in 2003 estimated the Summit Lake population to be about  12,000,000 Isoetes bolanderi plants. A 2004 survey found no significant change in population size. Rescue effect for this species from populations in the USA is highly unlikely.

 

Limiting Factors and Threats

Since Isoetes bolanderi is currently known from one 2-ha location in Canada, it is vulnerable to extirpation by a single catastrophic event. There is little impact evident at the Summit Lake site. Some impact by recreational use along a shoreline trail is evident and minor impact has also been noted from native ungulates. The most severe threat to the long-term viability of Isoetes bolanderi appears to be an intentional or accidental introduction of a toxic material (petrochemicals, herbicide, fertilizer, etc.), one occurrence of which could extirpate this species from the Canadian flora.

 

Special Significance of the Species

The sensitivity of Isoetes bolanderi to environmental change suggests that the population at Waterton Lakes National Park may provide a valuable indicator of ecological integrity.

 

Existing Protection

Isoetes bolanderi was previously assessed as a Special Concern species by COSEWIC and is Sensitive in the Canadian National General Status system. The existing population is entirely within Waterton Lakes National Park and is protected from removal, damage or destruction by the Canada National Parks Act and Regulations.

The current NatureServe conservation status is:

Global - G4 (apparently secure)

National - Canada N1 (critically imperiled), USA N4 (apparently secure)

Subnational –

S1 – AB, AZ (critically imperiled)
S1S2 – Navajo Nation (critically imperiled/imperiled)
S2S3 – WY (imperiled/vulnerable to extirpation or extinction)
S3 – NV (vulnerable to extirpation or extinction)
SNR (not ranked) – CA, CO, ID, MT, NM, OR, UT, WA.