Cliff paintbrush (Castilleja rupicola) COSEWIC assessment and status report: chapter 2

Logo of COSEWIC
COSEWIC
Executive summary

Cliff Paintbrush
Castilleja rupicola

Species information

Cliff paintbrush (Castilleja rupicola) is a perennial herb that grows up to 20 cm tall. The alternate leaves usually have 3 to 5 linear, spreading lobes. The inflorescence consists of a dense terminal spike consisting of small flowers surrounded by prominent and brightly coloured bracts (specialized leafy structures). The bright scarlet or crimson bracts are mostly deeply 5-lobed and much shorter than the greenish flowers.


Distribution

Castilleja rupicola ranges from southwestern British Columbia south to central Oregon. In Canada, the species is known only from the Chilliwack and Skagit river drainages in the Cascade Mountains of southwestern British Columbia and one historic site in the southern Coast Mountains.


Habitat

The species occurs on gravelly or stony soils, often in crevices on cliffs, rock outcrops and ridges in the subalpine and alpine zones. Vegetative cover in these habitats is sparse, usually less than 10% cover. On some subalpine and alpine slopes, C. rupicola occurs in gravelly openings in the Phyllodoce empetriformis-Cassiope mertensiana plant community.


Biology

Little information is available on the biology of Castilleja rupicola in British Columbia. Only basic reproductive facts have been compiled on the species. It is believed that most, if not all, Castilleja species require cross-pollination to set seed. Many species appear to be pollinated by hummingbirds, and bees may be important pollinators of other species. Seed production is likely to be of critical importance to Castilleja rupicola because it does not appear to be capable of reproducing by any other means. Short-range dispersal is likely by local scattering of seeds from the capsules by wind, birds and small mammals.

As with other species of Castilleja, it is likely that C. rupicola is a facultative parasite on the roots of other species. An examination of the roots indicate thatCastilleja species form special root-like connections called haustoria that attach to the roots of other plants, including other Castilleja plants (although they exhibit reduced vigour when grown with members of the same genus). These haustoria enable the parasitic plant to obtain supplementary nourishment from the host plant.


Population sizes and trends

A total of 15 historical and extant populations have been documented. There are three recently surveyed populations of Castilleja rupicola in the Skagit River valley in southwestern British Columbia. Eleven other records of the species, documented between 1901 and 1999, are known from both the Skagit and Chilliwack River valleys. A 1912 collection is also known from Mount Brunswick in the southern Coast Mountains. All of the latter 12 collections have virtually no information on population sizes. The three recently confirmed populations, observed in 2003, occur over a distance of 12.5 km. They range in size from one to five m2 and number from one to three plants.

Short- and long-term trends for these populations are unknown but can be expected to vary depending on the life span of the plants. Also, since the plants apparently only occur in small numbers, the success of seed germination and seedling survival will play a major role in these trends.


Limiting factors and threats

There are no major threats to populations of Castilleja rupicola at this time. However, if climate change predictions of higher global temperatures develop, it is possible that the subalpine/alpine habitats could be affected. It is not possible, at this time, to predict what specific changes to the habitat would occur.


Special significance of the species

Populations of C. rupicola in British Columbia are unique in that they are at the northern extent of theirgeographic range. This species is globally rare and has a relatively small global range consisting of less than 100 populations. Although no information on this species was found in a major ethnobotany database, other species of Castilleja are used extensively by Aboriginal peoples in North America.


Existing protection or other status designations

Castilleja rupicola is not covered under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), the Endangered Species Act (USA) or the International Union for Conservation of Nature (IUCN) Red Data Book. Globally, C. rupicola has a rank of G2G3 (imperiled/vulnerable). Provincially, C. rupicola is ranked by the Conservation Data Centre as S2 (imperiled) and appears on the British Columbia Ministry of Sustainable Resource Management’s Red List.

There is currently no specific endangered species legislation in place for the protection of vascular plants in British Columbia that have been given this S2 rank. Some of the populations of C. rupicola in British Columbia, however, are protected by the Provincial Park Act.

Page details

Date modified: