MacFarlane's Four-o'clock

Mirabilis macfarlanei

Description

MacFarlane's four-o'clock, Mirabilis macfarlanei, is a perennial plant that produces hemispherical clumps, 24-48 in (60-120 cm) in diameter, from a stout taproot. Stems are freely branched and swollen at the nodes. Opposite leaves, somewhat succulent, heart-shaped, and smaller toward the tips of the stems, are bright green above and gray beneath. The flower head is a cluster of four to seven large rose or purple, trumpet-shaped flowers.

In 1936, Ed MacFarlane, a boatman on the Snake River, pointed out the plant to two of his passengers. These botanists described the plant and named it after MacFarlane. The species was originally listed as Endangered in 1979, but, due to the ongoing success of recovery efforts, the species was reclassified to the less critical category of Threatened on March 15, 1996.

Habitat

MacFarlane's four-o'clock grows in sandy soils on open, steep slopes. Plants are widely scattered. Talus rock underlies the soil, which is susceptible to displacement by wind and water erosion. The habitat area is in a canyon corridor where the climate is warm and dry with a winter rainy season. The plant community is a grassy scrub, dominated by bluebunch wheatgrass, cheat grass, sand drop-seed, scorpion weed, desert parsley, hackberry, smooth sumac, yarrow, and rabbit bush.

Distribution

Most species of Mirabilis are found in the southwestern U.S., but MacFarlane's four-o'clock is an exception. Botanists suggest that, in a time of warmer climate, this species spread as far north as Oregon and Idaho, but, when temperatures cooled, only small populations survived in isolated canyons along the Snake River.

Currently, almost 1,000 plants are known on about 163 acres (66 hectares) in 18 locations. The plant occurs along 6 miles (9.6 km) of Hell's Canyon of the Snake River in Idaho and Wallowa County, Oregon; along 18 mi (29 km) of the Salmon River in Idaho County; and along 3 mi (4.8 km) of the Imnaha River in Wallowa County. Along the Snake and Imnaha Rivers, most of the plants occur on Nez Perce and Wallowa/Whitman National Forest lands. Most of the plants along the Salmon River occur on public lands administered by the Bureau of Land Management (BLM). The remaining plants are on public land.

From 1947, when futile searches were made for the plant, until 1977, when a small colony was found along the Snake River in Oregon, Mirabilis macfarlanei was thought to be extinct.

Threats

MacFarlane's four-o'clock has all the makings of a recovery success story. It was downgraded from Endangered to Threatened status in 1996, having been pulled back from the brink of extinction by aggressive recovery efforts.

Nevertheless, MacFarlane's four-o'clock still faces many natural and man-induced threats. Competition and crowding from more common plants appears to inhibit seed germination and growth. Spittle bugs, feeding on emergent growth, have depressed the vitality of many plants. A recreational trail runs through the middle of an Oregon population along the Snake River, making it vulnerable to casual collecting or careless trampling. This area has been designated as a National Recreational Area, and trail use has increased each year.

Conservation and Recovery

Conservation of MacFarlane's four-o'clock has involved conducting an exhaustive survey to locate other colonies of the plant; securing at least ten sites by acquisition or long-term agreements with landowners; and conducting proper management of the protected sites. If 10 natural sites cannot be located and secured, additional colonies of plants would be established by transplanting once suitable habitat has been identified. To protect genetic vigor, some plants from each population are to be maintained in a cultivated genetic reservoir and used to reseed thinning sites.

Improved livestock grazing management, research, the discovery of additional plant locations on public lands, and the stable condition of existing populations led the FWS to conclude that the plant's status had substantially improved, to the point where reclassification to Threatened status was appropriate. Interagency efforts have played a key role in the ongoing recovery. The BLM has reduced livestock grazing on its lands to a level that does not adversely affect the plant, and the Forest Service has excluded the plant's habitat from its grazing allotments or is requiring that livestock be removed before the plant starts to grow in the spring. Both agencies also are monitoring and evaluating plant population trends on their lands, and are cooperating with private land owners to conserve MacFarlane's four-o'clock plants and habitat on private lands.

Although the plant has been reclassified as Threatened, potential threats still remain, including lack of plant recruitment in some areas, insect predation, invasions of non-native plants, and the small size of some populations. MacFarlane's four-o'clock will continue to receive Endangered Species Act protection until full recovery has been achieved.

Contact

U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
911 N.E. 11th Avenue
Portland, Oregon 97232
http://pacific.fws.gov/

References

Johnson, C. A. 1982. "Habitat Management Plan for MacFarlane's Four O'Clock, Long Gulch Site." Bureau of Land Management, Coeur d'Alene District.

U.S. Fish and Wildlife Service. 1979. "Determination of MacFarlane's Four-O'Clock, (Mirabilis macfarlanei ) as an Endangered Species." Federal Register 44: 61786.

U.S. Fish and Wildlife Service. 1985. "Recovery Plan for the MacFarlane's Four-O'Clock, (Mirabilis macfarlanei )." U.S. Fish and Wildlife Service, Portland.