Clearwater National Forest |
BROAD-FRUIT MARIPOSA Calochortus nitidus Dougl. STATUS USFS Region 1: Sensitive USFWS: Species of Concern ICDC: G3/S3 INPS: Global Priority 3 TAXONOMY Family: Liliaceae (lily) Common name: broad-fruit mariposa Synonyms: Calochortus pavonaceus Fern. C. douglasianus Schult. Cyclobothra nitida Kunth. Description Broad-fruit mariposa is a perennial herb that grows from a large, deep-seated bulb. The erect stem can be up to 18 inches tall and usually has only one reduced leaf near the midpoint and a single large flat basal leaf that withers by flowering time. Reproductive plants have between one and four large, showy lavender to pink flowers, each with 3 petals and 3 sepals. Each petal has several long hairs and a deep purple crescent above a triangular shaped gland. The fruit is an erect capsule that is nearly circular with 3 distinct wings (Caicco 1992). This species reproduces by seed only. The new emergent plant looks very much like a blade of grass and will quickly wither. In future years plants that survive will appear as a large leaf that can be 20 cm long and 2.5 cm wide. These will also wither by anthesis in mid-late July, but will supply the plant with food well into the growing season. One to four flowers remain open, usually for 7-10 days. Wind appears to be the primary pollen vector, however, given the showey nature of the flower, pollinators are also suspected. There is no direct correlation between the total number of plants, the number of reproductive plants, and the number of fruits successfully produced in a given year. The explanation for this lies in the different causative factors underlying these characteristics of the population. The total number of plants appears to be most sensitive to the number of seedlings present, which may vary widely from year to year, although it is also influenced by survival rates among non-reproductive and reproductive plants (Caicco, 1992). The number of seedlings present is dependent on many factors including seed bank, seed germination rates, site quality, and annual climatic conditions (Harper, 1977). Not all bulbs capable of reproducing each year do so. In some populations the number of plants can vary tremendously from year to year. Distinguishing Features and Similar Species The deep purple crescent on the inside of each petal and the broad, orbicular fruit are indicative of this species. The species most resembling C. nitidus is C. macrocarpus (sagebrush mariposa), which is very comparable in flower size and color. However, this species has faint green stripes on the center of the petals and linear, unwinged fruits. In addition, the linear sepals are longer than the petals, while the sepals of C. nitidus are shorter than the petals. Another similar species is C. eurycarpus (big pod mariposa), which has a blueish/purple blotch on white to cream petals, while C. nitidus has a purple crescent on lavender petals. DISTRIBUTION Range Ownbey described the historic range of C. nitidus as "extending from the eastern border of the Palouse Prairie in Whitman County, WA., and Latah County, ID, to the Seven Devils Mts. above Riggins" (Hitchcock 1969). Low meadows and moist bottoms seemed to have been preferred locations. The Palouse Prairie community, which was its historical habitat has largely been converted to agricultural uses. It has been relocated in Washington state only recently after it was though to have been long extirpated there. Presently this species is limited to non-agricultural areas on the periphery of its former range; mainly in open woodlands of the Clearwater River Canyon to beyond Kooskia, and in the grasslands along the crests of the ridges bordering the Snake River Canyon to the Northern Seven Devils Mountains (Bingham 1987, Caicco 1992). These steep rocky sites and scattered small meadows are mostly confined to the canyon areas of Lewis, Nez Perce and Idaho Counties. Once believed to be confined to the Nez Perce National Forest, additional sites were located on the Lochsa and Palouse Ranger Districts of the Clearwater National Forest in 1989 and 1992 respectively. The Lochsa population is above the mouth of Canyon Creek near the Lost Irishman Mine and probably represents the eastern extension of this species' range (Lorain 1989). The Palouse population is in a small meadow along Hog Meadow Creek, south of Helmer. More recently additional populations have been found on the Palouse Ranger District. Three sites occur in the Elk Creek drainage. One of these is in the Bull Run RNA and another is nearby on lands proposed for addition to the RNA. The Palouse populations represent the northern limits of the range of this species. Habitat Broad-fruit mariposa has been extirpated from the low moist meadows and deep loessal soils of the Palouse Prairie. Today it is found only at sites not suitable for agricultural purposes, such as plateau grasslands; steep, thin soiled canyons and small forest openings amid ponderosa pine and Douglas fir forests. At a typical site, the soil is shallow and derived from fine-grained basaltic or andesitic bedrock lying near, or at the ground surface (Caicco 1992). The Canyon Creek population is found in a Pseudotsuga menziesii/Agropyron spicatum (Douglas fir/bluebunch wheatgrass ) habitat type (Lorain 1991). The Helmer site is in an open meadow with thin soil over basalt. The meadow is very wet in spring, but dry and hard by mid July when C. nitidus is present. There are scattered, small lodgepole pine and a unique plant community that contains some species more typically found on the Palouse Prairie. The Elk Creek populations occur in deep soil over basalt in canyon grasslands and bluffs. The dominant vegetation is Agropyron spicatum (blue-bunch wheatgrass). The sites are very wet in the spring, but become xeric by mid summer. REMARKS A species management guide for C. nitidus was written by Caicco (1992) for the Nez Perce National Forest. This plan mainly deals with grazing as most of this species' habitat is found in allotments. An Effects Analysis for this species was written in 1995 by Mike Hays as part of range allotment analysis for the Palouse Ranger District. The general model of the population biology of C. nitidus that is emerging from the data presented by Caicco is that of a species whose population density may fluctuate widely between years. There is no direct correlation between the total plant density, the number of reproductive individuals, or the number of reproductive structures produced. Reproductive success, as measured by the total number of fruits produced, may be high in years when the densities of plants and reproductive individuals are low or remain low in years when densities of plants and reproductive individuals are high. The main factor influencing successful fruit production is herbivory of floral buds, flowers, and immature fruits by grazing animals. These succulent structures, held upright by the erect stem, are an easy target for deer and livestock. Trampling of individual plants has also been observed. When these herbivores linger in a population for even a short period of time, they may effectively eliminate reproduction in the population for that year. Large populations do not seem seriously affected by grazing; however, smaller populations are more fragile and have been extirpated (Caicco 1992). Short-term effects on C. nitidus would include direct impacts to plants from grazing and trampling and continued competition with weeds. Over the longer term, the following factors are important. Field studies (Caicco 1992) have shown C. nitidus undergoes great population fluctuations with no relationship between population density and number of reproductive individuals and reproductive structures. This causes great population bottlenecks on a regular basis. Effects of herbivory can be substantially magnified on low population years. Other threats to survival include the small, fragmented, remote nature of many populations, which is the result of extensive agricultural development. These characteristics make populations susceptible to random events in survival, reproduction, environment change, catastrophic events, weed competition and genetic uncertainty. These factors become more important the smaller a population becomes and greatly increase the likelihood of extinction. Caicco (1992) noted that populations with around 50 plants are especially susceptible to extirpation within a few years. The Hog Meadow Creek population on the Palouse Ranger District number 59 plants in 1994. However in 1995 approximately 850 plants were counted. The timing of grazing activity appears to be important for the survival of this species, but inconsistency in the population size makes this difficult to quantify. The livestock rotation at the Hog Meadow Population was altered in 1995 to prevent grazing and trampling until after seed had set and the plants senesced for the season. The site needs to be revisited to see if this has had resulted in any changes in the population. REFERENCES Bingham, R.T. 1987. Plants of the Seven Devils Mountains of Idaho - an annotated checklist. USDA Forest Service, Intermountain Research Station Gen. Tech. Report INT-219, Ogden, UT. 146 pp. Caicco, S.L. 1992. Calochortus nitidus Species Management Guide. Unpublished report on file at: ID Dept. of Fish and Game, Conservation Data Center, Boise ID. 32 pp. plus appendices. Harper, J.L. 1977. Population biology of plants. Academic Press, New York. 892 pp. Hitchcock, C.L., A. Cronquist, M. Ownbey and J.S. Thompson. 1969. Vascular Plants of the Pacific Northwest, part 1. University of Washington Press, Seattle, WA. Lorain, C.C. 1991. Action plan for sensitive plant species on the Clearwater National Forest. Report to the Clearwater National Forest SO, Orofino, ID.
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