Mimulus clivicola

Mimulus clivicola Greenm.:
United States (North America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

United States

Origin: Unknown/Undetermined

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

Global Range: Mimulus clivicola is a regional endemic of the interior Pacific Northwest occurring in narrow river canyons in northern Idaho, west-central Idaho and adjacent northeast Oregon. In Idaho it occurs in portions of the St. Joe, North Fork Clearwater, Selway, Lochsa, South Fork Clearwater River canyons, the Elk Creek Falls vicinity, Carrill Peak, and the Bear-Cuprum area of west-central Idaho. In Oregon it occurs mostly in the North Pine Creek vicinity. (Lorain and Moseley 1990; Lorain 1991; Lorain 1992). See attached map of overall distribution (Lorain 1992).

Although most of the floras of the Pacific Northwest (Hitchcock et. al. 1959; Hitchcock and Cronquist 1973) describe this taxon as occurring in Washington, only one documented record by George Vasey in 1889 exists for the state and this occurrence has not been relocated. As of 1992 no extant locations are known from any portion of Washington (Lorain 1992).

The following characteristics help distinguish Mimulus clivicola from other small, annual, pink/purple-flowering Mimulus species occurring within its range, specifically M. breweri and M. nanus. M. breweri has rather inconspicuous, small (<10 mm), slender flowers, whereas, M. clivicola has larger (up to 2.5 cm), funnelform flowers. M. nanus has deep magenta flowers on pedicels 1-3 mm in length, has only a few hairs, and occurs in dry, open, often sandy or gravelly places, whereas, M. clivicola has distinctly pink flowers on pedicels 3-7 mm in length, is covered with rather dense sticky hairs, and occurs usually in more mesic sites. Neither M. breweri nor M. nanus has the distinct musky, sweet odor characteristic of M. clivicola (Lorain and Moseley 1989; Lorain and Moseley 1990).

Comments: Mimulus clivicola is restricted to a very specific set of habitat parameters. Plants typically occur in open pockets of moist, exposed mineral soil created by natural disturbances (erosion, big-game activity, etc.) or human-caused disturbances (roadcuts, etc.). They are almost exclusively found on southern exposures (southeast, south, southwest) with steep slopes (generally > 60%) in microhabitats that hold moisture during the spring.

Differences in elevation, soils, and plant associations exist among the northern Idaho, north-central Idaho, and northeast Oregon sites. Elevations range from 1600 to 4100 ft (mostly < 3600 ft) in northern Idaho, from 4200 to 5600 ft in west-central Idaho (with a single site extending to 7100 ft), and from 2500 to 5500 ft (mostly > 3500 ft) in northeastern Oregon. Soils range from deep, loose, decomposed granitics in northern Idaho, to deep to thin basaltics in west-central Idaho, to shallow, gravelly basaltics in northeastern Oregon (Lorain and Moseley 1990; Lorain 1991; Lorain 1992).

Most Mimulus clivicola populations in northern Idaho occur in Douglas-fir/Idaho fescue (Pseudotsuga menziesii/Festuca idahoensis), Douglas-fir/ninebark (Pseudotsuga menziesii/Physocarpus malvaceus), and grand fir/ninebark (Abies grandis/Physocarpus malvaceus) habitat types (Cooper et.al.1987). The plant associates in these habitat types include Collomia linearis, Clarkia pulchella, Sedum lanceolatum, Pteridium aquilinum, Collinsia parviflora, Achillea millefolium, Agropyron spicatum, and Triodanis perfoliata. Clarkia pulchella and Collomia linearis are excellent indicators for identifying potential habitat (Lorain and Moseley 1989; Lorain and Moseley 1990; Lorain 1991; Lorain 1992).

Most of the populations in west-central Idaho occur in a much drier sagebrush habitat type, the stiff sagebrush/Sandberg's bluegrass (Artemisia rigida/Poa secunda) habitat type (Tisdale 1986) with the following plant associates: Castilleja oresbia, Allium tolmiei var. persimile, Allium acuminatum, Lomatium dissectum, and Clarkia pulchella. Other populations were found in habitats similar to northern Idaho, Douglas-fir/mountain snowberry and Douglas-fir/ninebark with the following plant associates: Carex geyeri, Collinsia parviflora, Antennaria luzuloides, Collomia linearis, Potentilla glandulosa, Paeonia brownii, Amelanchier alnifolia, Spiraea betulifolia, and Penstemon payettensis (Lorain and Moseley 1990; Lorain 1991; Lorain 1992).

Most populations in northeastern Oregon occur as part of the Cusick's camas seepage plant community type (Camassia cusickii - CACU) (Johnson and Simon 1987), a commmunity type which tends to occur beneath basalt rims where seepage water persists into early summer. Plant associates in this community type include Camassia cusickii, Allium acuminatum, Calochortus eurycarpus, Sedum stenopetalum, Collomia linearis, Bromus tectorum, Collinsia parviflora, Achillea millefolium, Agropyron spicatum, Eriogonum heracleoides, and Perideridia bolanderi. Also, other annual Mimulus species, M. nanus, M. breweri, M. floribundus and M. guttatus, were often found in this community type. Camassia cusickii was the best indicator for identifying potential habitat in northeastern Oregon (Lorain and Moseley 1990; Lorain 1991; Lorain 1992).

Most biological/ecological information regarding Mimulus clivicola has been gathered from formal surveys in Idaho and Oregon which were initiated in the late 1980s by the Forest Service through contracts with the Idaho Natural Heritage Program. Also, a germination study was conducted by the University of Montana.

Mimulus clivicola is a spring-flowering annual that reproduces solely by seeds. Flowering begins in late May or early June and continues to mid-July. It is suspected that pollination is by ants, which may be attracted to the sweet, musky odor of the glandular hairs covering the plant (Lorain 1991).

Spring precipitation, availability of suitable microhabitat, and certain activities of big game animals seem to have high correlation with the germination and establishment of this species. Availability of spring moisture appears to be a necessary requirement. All known populations occur in moist microhabitats such as seepages caused by perched water tables, areas where water channels following rain, or in big-game tracks that hold water. Although these sites may dry out later in the summer, they provide a moist substrate in the spring for seed germination and flowering (Lorain and Moseley 1989; Lorain and Moseley 1990; Lorain 1991; Lorain 1992). Suitable microhabitat, patches of exposed mineral soil, which can result from natural causes such as erosion and the movements of big game or man-caused disturbances such as road-building, appears to be another necessary requirement. The movement of deer and elk not only create areas of exposed mineral soil and tracks that trap water, ideal conditions for germination and growth of the species, but also serve to disperse the seeds. Another aspect of big game activity which may be favoring the establishment of this species, is their grazing of cheatgrass (Bromus tectorum), a very competitive introduced winter annual. This may reduce competition for limited soil moisture on southern slopes, especially during droughty springs, and favor the establishment and growth of Mimulus clivicola (Lorain 1989).

Research on seed germination and early growth characteristics was conducted by researchers in the Department of Biological Sciences at the University of Montana (Pavek and Mitchell-Olds 1990). Seed germination required three weeks of stratification (moist, cool conditions of 100% humidity at approximately 40 degrees C). There was a high percentage of germination (no actual values given) occurring 12-19 days after the stratification period was complete. First flower buds developed at approximately 5 weeks, just after the second pair of leaves when the plants were only 0.5 inches tall.

As with many annuals, the number of flowering individuals in any particular growing season is highly correlated with annual weather conditions, in this case the presence of spring moisture, and may not be a good indicator of the long-term viability of the species. Research is needed on the seedbank, seed viability, and population dynamics to help understand the population biology of this species.

Mimulus clivicola is a spring-flowering annual that reproduces solely by seeds. Flowering begins in late May or early June and continues to mid-July. It is suspected that pollination is by ants, which may be attracted to the sweet, musky odor of the glandular hairs covering the plant (Lorain 1991).

United States

Rounded National Status Rank: NNR - Unranked

Rounded Global Status Rank: G4 - Apparently Secure

Reasons: A regional endemic, Mimulus clivicola is known from the interior Pacific Northwest and occurs in narrow river canyons in northern and west-central Idaho, northeastern Oregon, and historically in Washington. Threats are indirect logging activities, invasion of exotic weeds and consequent chemical control measures, grazing, the inundation of Dworshak Reservoir, potential resumption of mining activities, and recreational activities.

Comments: Both natural and human-caused factors play a role in threatening and/or eliminating populations of Mimulus clivicola (Lorain 1992). Natural threats include large-scale erosion and the process of natural succession. A certain amount of erosion or soil disturbance from animal movement appears to be necessary to create patches of exposed mineral soil, however, large-scale erosion could eliminate populations. The process of natural succession can increase shading and result in soil stabilization, factors that do not favor the growth of this species (Lorain 1991).

Human-caused threats include indirect logging activities, invasion of exotic weeds and consequent chemical control measures, grazing, the inundation of Dworshak Reservoir, potential resumption of mining activities, and recreation activities. Direct timber harvest activities probably do not threaten Mimulus clivicola because it occurs in non-timbered or very open stands which are unsuitable for intensive logging. However, some indirect logging activities, such as road building, road maintenance, and development or expansion of rock quarries, are associated with erosion and invasion of exotic species which pose distinct threats to Mimulus clivicola (Lorain and Moseley 1989). There are a number of highly competitive weeds that commonly occur in similar habitats as Mimulus clivicola, including knapweed, cheatgrass, and goatweed. The disappearance of many historical Mimulus clivicola sites can be directly attributable to road construction followed by the invasion of exotic weeds (Caicco 1988). Also, the chemical methods used to control these weeds may pose a further threat (Caicco 1987). Mimulus clivicola sites in west-central Idaho and adjacent northeast Oregon are frequently grazed which can result in trampling and soil damage if grazed when the soils are saturated (Lorain and Moseley 1990; Lorain 1992). Inundation by Dworshak Reservoir in north-central Idaho resulted in the loss of much suitable habitat. Resumption of mining at the presently inactive Lost Irishman Mine in the Lochsa River drainage, could pose a threat to one of the largest and best populations of Mimulus clivicola in north-central Idaho (Lorain and Moseley 1989). Recreationists pose a potential threat to those populations located near trails or existing roads (Lorain 1992).

Whereas certain disturbance activities, either natural or human-caused, may harm existing individuals, this species appears to tolerate and potentially benefit from these activities which may help to disperse seed and create suitable microsites for future populations.

Management Requirements: In order to adequately protect a given population of Mimulus clivicola, protection must center on the habitat of the species. Methods to protect the habitat include restriction of grazing or fencing populations in June and July to insure that plants won't be trampled prior to seed set, restriction of ORVs, no herbicide spraying, prohibition of road construction and maintenance, prohibition of fire and the establishment of an intact forest buffer of a minimum width of 100 ft from the population margins (Lorain 1992).

Specific management objectives are recommended for maintaining Mimulus clivicola populations at or above the minimum viable population level on Forest Service lands (Lorain 1992). In order to maintain this level, the populations must be self-sustaining, genetically stable, and adequately distributed throughout the species range. These objectives can be applied to management on other federal land, and state and private land as well. Following is a list of these objectives, revised to cover application to all areas where Mimulus clivicola occurs: 1) inform agency or private individual(s) of the locations of Mimulus clivicola on their land, 2) conduct further surveys in suitable habitat that has not yet been surveyed, 3) classify known populations into three protection categories, based on population size and distribution, 4) permanently protect and monitor key populations, and 5) maintain cooperation between federal/state agencies, private owner(s), and The Idaho Conservation Data Center and the Oregon Natural Heritage Data Base. Discussion and implementation of these objectives is described in the following paragraphs.

Private/public organizations or individuals conducting surveys for Mimulus clivicola (i.e., the Idaho Conservation Center, the Oregon Natural Heritage Data Base, The Nature Conservancy, private contractors, state/federal employees, etc.) should inform the landowner(s) of populations located on their land and advise them, if necessary, of the need to survey potential suitable habitat not yet surveyed.

State and federal agencies (i.e., Forest Service, Bureau of Land Management, State Department of Lands, Idaho Department of Fish and Game, etc.) may have computer geographic information systems already in place that they can query for potential habitat for Mimulus clivicola on their land.

New locations of Mimulus clivicola should be documented by specimens (if the population exceeds 50 individuals) that include both flowers and roots. The specimens should be sent to the Herbarium either at the University of Idaho or Washington State University for verification of their identity. Notification of confirmed sightings of Mimulus clivicola should be submitted to the state Natural Heritage Program for entry into their permanent data base on sensitive species. If sizable new populations and numbers of new sites are located, a reevaluation of the species status and conservation strategy would be warranted (Lorain 1992).

Monitoring Programs: Four permanent Ecodata plots (USDA Forest Service 1987) (see diagram of ecodata plot) were established within healthy Mimulus clivicola populations in four different river drainages (Elk Creek, North Fork of the Clearwater, Lochsa, and Selway) during the 1989 field season. In addition to the complete ecodata information collected at each plot, counts were made of all plants, including seedlings, that fell within a 2-meter wide belt transect running in a north-south direction through the center of the circle. These sites were recounted in 1990 and 1991 (see Table 1 for data on the number of flowering individuals counted for each year) (Lorain 1992).

Management Research Programs: Research on seed germination and early growth characteristics was conducted by researchers in the Department of Biological Sciences at the University of Montana (Pavek and Mitchell-Olds 1990). Seed germination required three weeks of stratification (moist, cool conditions of 100% humidity at approximately 40 degrees C). There was a high percentage of germination (no actual values given) occurring 12-19 days after the stratification period was complete. First flower buds developed at approximately 5 weeks, just after the second pair of leaves when the plants were only 0.5 inches tall.

Management Research Needs: For a successful management strategy, new populations should be classified into the following protection categories (Lorain 1992): 1) Protection Category 1 - Key populations that will be permanently protected. Populations in this category should be the largest (> 500 individuals), most vigorous populations that occur in relatively undisturbed habitats where existing and/or future monitoring is considered important. Consideration should also be given to populations that fall within existing special designation areas (i.e., Recreation Areas, Research Natural Areas, etc.) and disjunct or peripheral populations that define the geographic range of the species and may represent important genetic variability.

2) Protection Category 2 - Populations managed within a multiple-use framework with some considerations given to their maintenance. Populations in this category are usually of moderate size (200-500 individuals), have been naturally and/or artificially disturbed in the past and may provide important information concerning the effects of disturbance.

3) Protection Category 3 - Populations that could be sacrificed if necessary, if there is some assurance that the best populations are being protected. These populations are usually the smallest (< 200 individuals) and are considered marginal because of size, low density, and/or occur on non-pristine sites.

(Known populations of Mimulus clivicola have been classified into these 3 categories. Refer to Lorain (1992) for the specific locations and their protection category designations.)

To insure proper category designation of newly discovered sites, a detailed assessment of existing and surrounding habitat and annual site visits are recommended. Since there are wide fluctuations in numbers of observed individuals from year to year, annual population counts can provide a more accurate picture of the true population size. However, knowledge of the seedbank as well, would provide the best information on population size.

Biological Research Needs: Research is needed in the following areas: 1) relationship between population levels and climate/available moisture, 2) relationship between population levels and big game wintering and migration pattern and the creation of exposed mineral soils, 3) the role of the seedbank and seed viability as it relates to the population biology and long-term population viability, 4) the cumulative effect of human activities on habitat loss, and 5) pollination studies.

New information regarding Mimulus clivicola has been gathered in the last decade through inventory surveys and the habitat and population data collected in conjunction with those surveys, Ecoplot data collected over a three-year period on four populations, and the seed germination studies conducted at the University of Montana. This information in conjunction with the research needs mentioned in the previous section provide the guidelines for a research program.

Comments: Family: Scrophulariaceae (Figwort Family), Synonymy: Eunanus clivicola, Heller (Muhlenbergia 1(4): 47-62, 1904), Citation: Greenman, J.M. 1899. Northwestern plants, chiefly from Oregon. Erythea, 7(11): 115-120, Type specimen: Sandberg, MacDougal, and Heller. No. 586. Idaho, slopes near the foot of Weissner's Peak, Kootenai County, 8 July, 1892.

Stewardship Overview: Mimulus clivicola is a limited regional endemic with very specific habitat requirements. Despite the number of new populations found during recent surveys, most populations are less than 200 individuals and many populations occur within areas where human habitat-altering activities are taking place. Both natural and human-caused factors play a role in threatening and/or eliminating populations of Mimulus clivicola (Lorain 1992).

Stewardship should encompass all survey, monitor, research and management needs aimed at the protection and perpetuation of Mimulus clivicola. Additional surveys are needed, not only on certain portions of Forest Service land, but also on private lands, to fully delineate the extent and range of this species. Monitoring should continue annually on the four Ecoplots already established and should be expanded to include key populations given permanent protection. Research should focus on the relationship between population levels and annual weather patterns and big game activities, the role of seedbank, seed viability, and pollinators on the long-term viability of the species, and the cumulative effect of human activities on habitat loss. Management activities should include notification to landowners of population locations on their land and the need for additional surveys if necessary, classification of populations into protection categories, permanent protection of key populations, and cooperation and information exchange between public and private landowners and state Heritage Programs.