|Constance & Rollins|
|Edward Guerrant, Ph.D.|
The following Participating Institutions are custodians for this species in the CPC National Collection:
Rae Selling Berry Seed Bank & Plant Conservation Programs
Cincinnati Zoo & Botanical Garden
The conservation of Mirabilis macfarlanei is fully sponsored.
Edward Guerrant, Ph.D. contributed to this Plant Profile.
This showy plant is quite something if you encounter it in the dry areas of Eastern Oregon and Western Idaho. Often growing on dry, steep slopes high above the river, this four-o'clock, with bright magenta flowers and purplish stems, stands out on the brownish hillsides.
Mirabilis macfarlanei was listed as Endangered by the US Fish and Wildlife Service in 1979. It was threatened by many things, including: trampling, grazing, disease, insect damage and horticultural collecting. An initial recovery plan was created in 1985. It called for baseline studies, determination of population trends, and periodic sampling of populations. The species was downlisted to Threatened in 1996 due to the discovery of additional populations and successful recovery efforts. A revised recovery plan was finalized in 2000.
The protection of Mirabilis macfarlanei is especially important because it is host to a rare moth that was discovered in 1983. This Heliodinid moth (Lithariapteryx sp.) is host specific to M. macfarlanei. The moth larvae only feeds on the leaves and flowers of Mirabilis macfarlanei (Baker 1985). In the interests of biodiversity, it is important to preserve both the rare moth and the rare four-o'clock. Because the moth's feeding preferences have the capability of reducing reproduction of the four-o'clock, it is important to protect large numbers of plants. With larger numbers of plants, there will be a greater chance for plants to reproduce.
Above ground, the plant does not look very large. It may consist of a few trailing branches up to a couple of feet across. However, underground, the plant has a thick taproot that may grow up to 8 feet deep! This large underground structure enables it to remain dormant in poor growth years or to recover from above ground disturbances. For example, in 1997, an accidental herbicide spraying by the county weed management board in Idaho severely impacted several thousand stems of Mirabilis macfarlanei on both federal and private land. At least 2,750 of the stems on federal land showed heavy damage from the spraying, but in 1998, monitoring showed that many of the plants had survived (USFWS 2000). The long-term effects are unknown. Seeds collected that year from the affected populations smelled strongly of herbicide, indicating that the herbicide may have impacted seeds produced that year (Andrea Raven, pers. comm. 2001).
The species was named after Ed MacFarlane, who was a riverboat pilot on the Snake River for over 30 years. Ed MacFarlane did not discover the species. It was shown to him by Harold St. John, a botanist, on a trip up the Snake River. For unknown reasons, St. John did not publish his find. Later, Ed MacFarlane showed two other botanists, Lincoln Constance and Reed Rollins, the plant. They described the species and named it after the pilot (Pilz 1978 in Kaye and Meinke 1992).
Distribution & Occurrence
Found growing primarily on west or southeast facing slopes in the canyon areas of the Imnaha, Snake, and Salmon Rivers. Slopes range from extremely steep to nearly flat, but are always covered with sandy to talus (gravel and cobble) substrate. Elevations range from 1000 to 3000 ft (300-900 m).
OR: Blue Mountains (Imnaha River and Snake River)
ID: lower Salmon River Canyon and Snake River
|Currently 11 populations in Idaho and Oregon with a total population and estimated 8,000 to 9,000 individuals (based on 39,00 to 44,000 stems) (Craig Johnson in litt. 1999 in U.S. Fish and Wildlife Service, 2000).
Because of clonality, it is difficult to determine the number of genetic individuals (Barnes et al. 1997).
Conservation, Ecology & Research
The plants are at least partially self-compatible. Insect pollination may not be crucial to short-term population survival, as plants can produce seed without them. However, insect pollination is crucial to the long-term survival of the species. Without pollinators, inbreeding depression may develop and lead to a decrease in population viability (Kaye et al. 1990). This will hinder the species' ability to adapt to changing conditions.
Habitat occupied by Mirabilis macfarlanei was found to have a greater density of native grasses than adjacent unoccupied habitat (Kaye 1992). Unoccupied habitat contained far more exotic (non-native) species such as yellow starthistle (Centaurea solstitalis), toadflax (Linaria genistifolia) and spotted knapweed (Centaurea maculosa). This suggests that M. macfarlanei populations require high quality native grasslands to ensure their long-term survival.
Mirabilis macfarlanei is host to a rare moth whose larvae depend on the leaves for food and survival (Kaye 1990). The larvae eat the leaves of the plant as well as the floral parts. The large magenta flowers are pollinated by bumblebees (Bombus fervidus), Tetralonia sp. and Anthophora sp. (large solitary bees) (Kaye et al. 1992).
The long, thick taproot helps the plant survive unfavorable climactic conditions as well as damage and disturbances. The underground stems of Mirabilis macfarlanei can survive most natural fires, especially since they most occur later in the summer, when the plant is dormant. (Based on conversations with Craig Johnson, Cottonwood District BLM, concerning an Idaho population affected by wildfire).
Invasion of exotic (non-native) plants (USFWS 2000).
Collection for horticultural use (Meinke 1982).
Damage to plants and habitat from human trampling, Off-road vehicle (ORV) use, construction a
Preliminary monitoring on the effects of cattle on Mirabilis macfarlanei. Two plots at one location were placed inside a cattle exclosure (non-grazed) and three were placed outside (grazed) to compare. Plant height was significantly greater in plots inside the cattle exclosure than outside. However, plant diameter and number of inflorescences did not differ with grazing treatment (Kaye 1995).
Determination of breeding system. Inflorescences were bagged before flowers opened. Seed was collected from both bagged and un-bagged inflorescences. Bagged flowers did produce seed, indicating that the species is self-compatible. Seed set was slightly greater in un-bagged inflorescences than in bagged, indicating that insects do pollinate the flowers and contribute to higher reproduction levels than obtained through selfing (Kaye et al. 1990).
Genetic studies of Mirabilis macfarlanei utilizing isozymes. M. macfarlanei has lower genetic diversity compared to other plant species with similar life histories. Gene flow was found to decrease as the distance between populations increased. The different populations were found to have relatively high levels of genetic differentiation and small populations were found to have alleles (genes) that were not present in larger populations (Barnes et al. 1994).
Genetic analysis, using isozymes, of the genetic diversity between and among 8 populations and the extent of clonality in 4 populations from Idaho (Barnes et al. 1997).
Initial germination trials at the Berry Botanic Garden indicated a preference for alternating temperatures. Seeds were subjected to four treatments: Either direct placement into 68F (20C) or alternating 50/68F (10/20C) or 8 weeks of cold stratification followed by 68F (20C) or 50/68F (10/20C). Treatments placed in alternating 50/68F showed 40% germination while both treatments placed in 68F showed 20% germination. Cold stratification had no effect. These results are not conclusive as seed numbers were low (BBG File).
Habitat Management Plans have been developed and monitoring has occurred for several populations in Idaho by the BLM (USFWS 2000).
Several sites on Forest Service land have been fenced to exclude cattle (USFWS 2000).
Seed from sites in Idaho and Oregon stored at The Berry Botanic Garden.
Approximately 400 rhizomes were transplanted from an area of land slides and road construction to a Research Natural Area in 1998 and 1999 (USFWS 2000).
60 rhizomes were transplanted to a fenced exclosure within a Research Natural Area (RNA) in 1988 (USFWS 2000).
Fence populations to prevent grazing (Meinke 1982).
Monitor Mirabilis. macfarlanei population trends and habitat conditions (USFWS 2000).
Conduct surveys in potential habitat areas. Manage and protect any newly discovered populations (USFWS 2000).
If warranted, establish and maintain new populations on areas where Mirabilis macfarlanei has been extirpated (USFWS 2000).
Random samples of soil should be gathered to test for the presence of a soil seed bank (Kaye et al. 1992).
Study the relative contribution of sexual versus vegetative reproduction further (USFWS 2000).
Control invasive Bromus tectorum (cheatgrass) (USFWS 2000).
Manage herbicide and pesticide use (USFWS 2000).
Conduct demographic monitoring if populations decline by more than 25% over a 3 year period (USFWS 2000).
Conduct research on pollinators (USFWS 2000).
Conduct inventory of suitable habitat, especially on the Oregon side of the Snake River, to locate new populations.
Determine optimum germination procedures.
Determine propagation and reintroduction protocols.
Brooks, P. 1991. Sensitive Plants of the Malheur, Ochoco, Umatilla, and the Wallowa-Whitman National Forests. USDA-Forest Service, Pacific Northwest Region.