(Photo by Dave Clark)

Rubber Rabbitbrush and Fallen Limber Pine

The dominant tree in the northern half of Craters of the Moon is limber pine (Pinus flexilis). In the southern half Juniper (Juniperus spp.) is the dominate tree species.

Limber pine habitat provides important cover and food for wildlife. The large, wingless seeds of limber pine have a high energy content and provide a critical food source for rodents and birds. Clark's nutcrackers are major dispensers of seeds, caching groups of seeds in the ground. These caches are relocated by Clark's nutcrackers, pilfered by rodents or are forgotten and germinate under favorable conditions. Limber pines are more abundant on aa than pahoehoe flows, but in both cases are able to grow where water collects, and especially where the trees receive protection from the fierce high desert winds.

In the southern portions of the monument, stands of Rocky Mountain juniper (Juniperus scopulorum) and Utah juniper (Juniperus osteosperma) provide scarce structure and food source for birds and other wildlife. Although many were harvested by early settlers, some rare stands of old growth junipers (700+ years old) remain on the lava fields.

A few other species of trees are also found here, but in very limited numbers and geographical areas. The portion of the monument north of U.S. Highway 20/26/93 contains some Douglas-fir and upland quaking aspen stands. Douglas-fir forests are found on the relatively steep, north-facing slopes of older cinder cones and along Little Cottonwood Canyon. Quaking aspen groves are in upland sites away from permanent stream courses.

Several shrubs typically associated with mountain or riparian habitats are uniquely able to find similar growing conditions in the cracks of barren lava flows at Craters of the Moon. Examples include the fern bush and syringa. In order to resist being robbed of moisture by wind, the fern bush (Chamaebatiaria millefolium) grows inside deep crevices in the lava. It has aromatic leaves that resemble the fronds of ferns and that contain an oily substance which also helps the plants retain moisture. Native Americans rubbed the leaves over their bodies to repel insects. Deep crevices in the lava flows also provide the soil, moisture, and lower temperatures needed for the syringa (Philadelphus lewisii) plant to grow. Named after Meriwether Lewis of Lewis and Clark fame, this medium-sized shrub bears numerous large white flowers with four petals. It is very fragrant and serves as the state flower of Idaho.

Other common shrubs include sagebrush, antelope bitterbrush, and rubber rabbitbrush (Chrysothamnus nauseosus).

The dominant species of sagebrush in the northern part of Craters of the Moon is mountain big sagebrush (Artemisia tridentata ssp. vaseyana), which is part of a sagebrush steppe ecosystem that includes different types of grasses. Basin big sagebrush, Wyoming big sagebrush (Artemisia tridentata spp. wyomingensis), three-tip sagebrush (Artemisia tridentata spp. tridenta), low sagebrush (Artemisia arbuscula spp. arbuscula),and early low sagebrush (Artemisia arbuscula spp. longiloba) are also found here.

Antelope bitterbrush provides browse for mule deer during the summer months, is a frequent host of thousands of tent caterpillars, and is identifiable by abundant yellow flowers and small, three-lobed leaves.

Rubber rabbitbrush grows to two meters tall and produces yellowish-green flowers from July to September. Native Americans made chewing gum by pulverizing its wood and bark. Rubber rabbitbrush can also be used to make tea, cough syrup, yellow dye, chest pain medicine, and is a small commercial source for rubber extraction.