Silene spaldingii

Spalding's Silene

Taxonomy

General Description: Perennial with a simple or branched rootcrown and stems up to 45 cm tall. There are 4 - 7 pairs of sessile, broadly lance-shaped leaves, 6 - 7 cm long, up to ca. 1 cm wide, and gradually reduced in size upward; herbage is long-hairy and very sticky. There are few to many flowers in a leafy, somewhat open inflorescence; the tubular calyx, ca. 15 mm long, has 10 nerves on the surface and is very sticky; corolla has 5 separate, white petals, each composed of a narrow claw ca. 15 mm long, expanding into a broadened blade above; only the entire or shallowly-lobed blade with 4 tiny wings at the base protrudes beyond the mouth of the calyx. Fruit is a capsule, 10 - 15 mm long, filled with numerous tiny seeds.

Technical Description: Villous-tomentose and more or less viscid-pubescent perennial from a simple or branched caudex, 2 - 6 dm tall; cauline leaves 4 - 7 pairs, oblanceolate below to lanceolate above, 6 - 7 cm long, 0.5 - 1.5 cm broad, sessile and slightly connate; flowers several to many in a leafy and usually compact cyme; calyx tubular-campanulate, about 15 mm long at anthesis, becoming more nearly clavate-campanulate in fruit, 10-nerved; corolla white, the claw of the petals about 15 mm olong, not auriculate above, the blade very short, ovate, about 2 mm long, entire to shallowly emarginate; appendages 4 (5 or 6), ovate-lanceolate, about 0.5 mm long; carpophore about 2 mm long, glabrous; styles 3; capsule 1-celled; seeds light brown, about 2 mm long, corrugate-wrinkled and inflated. Chromosome number 2N=24 (adapted from Hitchcock et al. 1964).

Diagnostic Characteristics: Superficially similar to several congenerics. It can be distinguished from other perennial Silene species by the very sticky foliage and petal blades that are very short and entire or only shallowly lobed.

Infraspecific Taxa:

Similar-appearing Taxa: Silene spaldingii is similar in appearance to several congenerics. Flowers are needed for positive identification.

Silene spaldingii flowers are distinguished by a long, sticky-glandular calyx tube, petal blades about 2 mm long that are only shallowly emarginate/bilobed and containing 4 - 6 appendages.

Silene scouleri is also a very glandular species, however, it has bilobate petals with only 2 appendages.

Silene oregana has petal blades deeply 4-lobed and much longer and narrower.

Silene cseri is an annual species with long petal blades and foliage that is often not sticky-pubescent.

Silene douglasii has more slender stems and leaves, and rarely has glandular pubescence.

Identification of this Taxon in Idaho: Vegetatively, Silene spaldingii appears similar to several other perennial, very sticky (glandular) congenerics with overlapping ranges and habitat requirements. In Idaho, S. scouleri and S. oregana are probably the most likely species to be confused with S. spaldingii. Flowers in good condition (to observe size and shape of flower petals and their appendages) are very important for accurate identification.

Comments (Global): This is a distinct species.

Comments (Idaho):

Status

Global: Throughout its range, much of the Palouse Prairie grassland habitat of Silene spaldingii has been converted to crop agriculture or pastureland. Although probably once widespread in the Palouse region, S. spaldingii is now known from mainly small, fragmented sites on the periphery of its former range. Most remaining populations are small and threatened by weed invasion (including yellow starthistle in places), herbicide treatment (particularly because many populations are small and located near farmlands and roads), and livestock grazing (Gamon 1991; Lorain 1991; Schassberger 1988). Activities such as road construction and maintenance, gravel mining, off-road vehicles, and urban developments are additional threats (Lorain 1991; Heidel 1995).

Silene spaldingii is presently known from a total of 63 occurrences, supporting an estimated 14,000 individuals (Heidel 1995). Only seven occurrences are known to contain more than 100 individuals. The large population located within The Nature Conservancy's Dancing Prairie Preserve in northwestern Montana is the only site with more than 500 plants. There are 31 occurrences in Washington, 14 in Oregon, 10 in Idaho, and 8 in Montana. At least nine occurrences are considered extirpated (Heidel 1995), and declining populations have been documented at several other sites (Lesica 1992; Heidel 1995).

Silene spaldingii is a serious conservation concern in all four states where it occurs. It is listed as endangered by the Washington Natural Heritage Program, and threatened by the Montana Natural Heritage Program. It is a candidate for state listing as threatened or endangered in Oregon, while in Idaho, it is on the Idaho Native Plant Society's globally rare list. The Association of Biodiversity Information's global rank for S. spaldingii is 2. This rank includes taxa imperiled because of rarity or because of other factors demonstrably making it vulnerable to extinction. It has been assigned a rank of 1 for the states of Oregon, Idaho and Montana. This rank includes state taxa critically imperiled because of extreme rarity or because of some factor of its biology making it especially vulnerable to extinction. The state rank for Washington is 2. Status reports have been completed for Washington (Gamon 1991), Idaho (Lorain 1991), and Montana (Schassberger 1988). Until the U. S. Fish and Wildlife Service recently revised their candidate system, S. spaldingii was a federal category 2 candidate for listing under the Endangered Species Act. Under the revised system, it is no longer a federal candidate species. It is a U. S. Forest Service Region 6 sensitive species.

Idaho: The Idaho Native Plant Society places Silene spaldingii in the globally rare category of the state's rare plant list.

Distribution

Global: Silene spaldingii is endemic to mesic grasslands of the Palouse Prairie region in eastern Washington and adjacent portions of northeastern Oregon and north-central Idaho, and also in northwestern Montana. In addition, one Montana population extends into adjacent British Columbia.

Idaho: In Idaho, Silene spaldingii occurs in the Palouse Prairie region in Nez Perce, Lewis, and adjacent Idaho counties.

Habitat

Silene spaldingii habitat

Elevation (Global): 1900 to 3600 feet

Elevation (Idaho): 2800 to 4200 feet

Global: Silene spaldingii is restricted to Festuca idahoensis habitat types and phases throughout its range. These areas are often referred to as Palouse Prairie. Sites are often near lower treeline, or near scattered ponderosa pine trees. Populations have been found on all aspects, but there seems to be a preference for northerly-facing aspects. It occurs at elevations ranging from about 1900 to 3600 feet, and on flat to steep slopes. Soils are almost always productive silt/loams (loess) that are moderately deep and sometimes gravelly (Gamon 1991; Lorain 1991).

Idaho: In Idaho, Silene spaldingii occupies Palouse Prairie and mesic canyon grassland communities (Lorain 1991; Mancuso and Moseley 1994). It is associated with relatively undisturbed slopes or flats in swales and drainages, upper canyon slopes, and in small strips of native vegetation surrounded by cultivated fields. Sites often occur near lower treeline or scattered Pinus ponderosa trees. The vegetation is dominated by Festuca idahoensis, with numerous perennial forbs and scattered shrubs such as Rosa nutkana and Symphoricarpos albus. It occurs within the following habitat types: Festuca idahoensis/Rosa nutkana, F. idahoensis/Symphoricarpos albus, Crataegus douglasii/S. albus, Pinus ponderosa/S. albus, and F. idahoensis/Koeleria cristata. Soils are mostly productive silt/loams (loess) with occasional loams and skeletal silt/loams. These mesic prairie habitats also support two other rare regional endemics, Aster jessicae and Haplopappus liatriformis.

Ecology

Global: Silene spaldingii most frequently occurs in relatively intact climax or successionally advanced mesic grassland communities (Lorain 1991). It does not occur at sites where the native vegetation has been displaced by aggressive weeds. It is apparently tolerant of light to moderate grazing (Schassberger 1988). Lesica (1994) found that prescribed burning at a site in Montana increased growth, recruitment and flowering of Silene spaldingii.

Idaho: See Global Ecology comments.

Reproduction

Global: Silene spaldingii is a partially self-compatible, hermaphroditic perennial. Reproduction is apparently via seed only, as rhizomes or other means of vegetative propagation are lacking. Seeds appear to require cold stratification, so germination occurs mainly in the spring. Rosettes are formed the first year and flowering may occur during or after the second season. Flowers are protandrous (Lesica and Heidel 1996). Anthers mature and dehise pollen first. During this time, the styles are unexpanded, and the unexposed stigmatic surfaces are held well below the level of the anthers. After the anthers shrivel and fall from the filaments, the three styles expand and the stigmas become receptive. Each flower persists for two to several days, and two or more flowers may be in bloom on the same plant, so geitonogamous pollination is possible. This system promotes outcrossing while allowing the possibility of selfing (Lesica 1991; 1993). The bumblebee, Bombus fervidus, appears to be the only significant pollination vector for S. spaldingii throughout its range (Lesica and Heidel 1996). At least at some populations, S. spaldingii appears to be subject to pollinator limitations, inbreeding depression, and a large genetic load (Lesica 1991; 1993).

Idaho: See Global Reproductive comments.

Phenology (Idaho): Germination takes place mainly in the spring. Flowering occurs in mid-summer or later, peaking around the third week in July. Plants on exposed southerly slopes flower first, while those on north and east aspects bloom later. Fruit and seed maturation occurs in August, with seed dispersal taking place in late August to early September (Lorain 1991).

Management

Global: Throughout its range, most occurrences of Silene spaldingii are located on private land. In Washington, occurrences are also located on Washington State University, Washington Department of Natural Resources, Washington State Parks and Recreation, and BLM land. A portion of the largest occurrence known is located on The Nature Conservancy's (TNC) Dancing Prairie Preserve in northwestern Montana. Another occurrence occurs on TNC's Garden Creek Preserve in Idaho. Silene spaldingii occurs on Indian Reservation land in Montana and Idaho. Occurrences are known from Forest Service land in Oregon, and BLM land in Idaho. Preliminary genetic analysis (Baldwin and Brunsfeld 1995), pollination and reproductive studies (Lesica 1988; 1991; 1993; Lesica and Heidel 1996), fire ecology research (Lesica 1992; 1995), and monitoring studies (Lesica 1988) have been conducted for S. spaldingii. Several of these projects are ongoing.

Idaho: Five of the ten Idaho occurrences of Silene spaldingii are located on private land. Two occurrences are located on tribally-owned land within the Nez Perce Indian Reservation. Two occurrences are on The Nature Conservancy's Garden Creek Preserve at Craig Mountain. Except for the Garden Creek Preserve, there has been no monitoring or other management activities concerning this species in Idaho.

Inventory

General Comments (Idaho): The first and most comprehensive systematic survey for Silene spaldingii in Idaho was conducted by C. Lorain (1991) with the Idaho Conservation Data Center in 1990. The survey was part of a state conservation status report being prepared for the U. S. Fish and Wildlife Service. Additional surveys were conducted at Craig Mountain by Idaho Department of Fish and Game and The Nature Conservancy botanists during the period 1993-1995. The BLM has also conducted field inventories associated with regular project clearance and related work.

Inventory Needs (Idaho): Several Idaho occurrences have not been revisited since 1990, or earlier. Population reassessments need to be completed at these sites.

References

Atwood, D., and N. Charlesworth. 1987. Status report for Silene spaldingii. Not paged.

Baldwin, C. T., and S. J. Brunsfeld. 1995. Preliminary genetic analysis of Silene spaldingii (Spalding's catchfly), a candidate threatened species. Wildland Plant Ecogenetics Cooperative, University of Idaho, in cooperation with Montana Natural Heritage Program. Not paged.

Gamon, J. 1991. Report on the status in Washington of Silene spaldingii Wats. Report prepared for Washington State Department of Natural Resources by the Washington Natural Heritage Program, Olympia. 53 pp.

Heidel, B. 1979. Endangered and threatened plants in the Northern Idaho BLM District. 100 pp.

Heidel, B. 1980. Report for Silene spaldingii. 11 pp.

Heidel, B. 1995. Preliminary status report update for Silene spaldingii (Spalding's catchfly), a candidate threatened species. Montana Natural Heritage Program, Helena. 11 pp. plus appendices.

Heidel, B., and P. Lesica. 1993. Conservation strategy for Silene spaldingii. Unpublished grant proposal prepared for The Nature Conservancy. 3 pp.

Hitchcock, C. L., A. Cronquist, M. Ownbey, and J. W. Thompson. 1964. Vascular plants of the Pacific Northwest. Part 2: Salicaceae to Saxifragaceae. University of Washington Press, Seattle. 597 pp.

Hitchcock, C. L., and B. Maguire. 1947. A revision of the North American species of Silene. University of Washington Publications in Biology, Vol. 13. University of Washington Press, Seattle. 73 pp.

Kruckeberg, A. R. 1961. Artificial crosses of western North American Silenes. Brittonia 13: 305-333.

Lesica, P. 1988. A preliminary study of the pollination biology of Spalding's Catchfly in the Tobacco Valley, Lincoln County, Montana. Prepared for: The Nature Conservancy, Montana/Wyoming Office, Helena, MT. Montana Natural Heritage Program, Helena. 5 pp.

Lesica, P. 1988. Germination requirements and seedling biology of Spalding's Catchfly (Silene spaldingii). Prepared for: The Nature Conservancy, Montana/Wyoming Office, Helena, MT. Montana Natural Heritage Program, Helena. 2 pp.

Lesica, P. 1988. Monitoring Silene spaldingii on Dancing Prarie Preserve: 1988 progress report. Prepared for: The Nature Conservancy, Montana/Wyoming Office, Helena, MT. Montana Natural Heritage Program, Helena. 4 pp.

Lesica, P. 1988. Monitoring Silene spaldingii on Wild Horse Island: 1988 progress report. Prepared for: The Nature Conservancy, Montana/Wyoming Office, Helena, MT. Montana Natural Heritage Program, Helena. 3 pp.

Lesica, P. 1991. Inbreeding depression and the importance of pollinators to the threatened plant, Silene spaldingii (Caryophyllaceae). Prepared for: The Nature Conservancy, Montana Field Office, Helena. Montana Natural Heritage Program, Helena. 15 pp.

Lesica, P. 1992. The effects of fire on Silene spaldingii. 1992 progress report. Montana Natural Heritage Program, Helena. 14 pp.

Lesica, P. 1993. Loss of fitness resulting from pollinator exclusion in Silene spaldingii (Caryophyllaceae). Madrono 40(4): 193-201.

Mancuso, M., and R. Moseley. 1994. Vegetation description, rare plant inventory, and vegetation monitoring for Craig Mountain, Idaho. Unpublished report prepared for Bonneville Power Administration. 146 pp. plus appendices.

Schassberger, L. A. 1988. Report on the conservation status of Silene spaldingii, a candidate threatened species. Montana Natural Heritage Program, Helena. 71 pp.

Siddall, J. L., and K. L. Chambers. 1978. Status report for Silene spaldingii. Not paged.

Author: M. Mancuso
Updated: 96-05-24
Produced by The Nature Conservancy, the Natural Heritage Network, and the Idaho Conservation Data Center.