Single-leaf pinyon (Pinus monophylla) is unique among American Pinus species in having single leaves rather than bundles of leaves or needles. The needles are greyish green with a whitish tinge and are round. They are stiff, curved toward the branch and prickly. The season’s growth of needles remains on the tree for about 7 or 8 years, but can persist for 12 years.
Mature single-leaf pinyon trees have short trunks that are rarely straight and a wide, rather flat crown of short, heavy, twisted and bent branches. The bark of young trunks and twigs is dull grey while old trunks are roughly and irregularly furrowed with bark nearly an inch thick, and thin, close, dark to reddish brown scales. Single-leaf pinyons are usually not over 25 feet in height unless in protected or otherwise favorable conditions. Slow growing, this native regularly lives to 100 years and can survive for up to 400 years.
Cones mature in August of the second season and the seeds are shed about a month later. Single-leaf pinyon cones are egg-shaped with thick scales raised at the ends into high, broad-based pyramids with rounded tops. First year cones are greenish and mature to a yellow-brown color. The empty cones fall from the tree in winter or spring.
Single-leaf pinyon seeds are a dark chocolate brown. Their narrow wings remain attached to the cone scales when the seeds are released. The oily, nutritious seeds were a Native American staple and even today pinyon (pine) nuts are eaten. Leonard and I collected handfuls of seeds and enjoyed a trailside treat.
The yellowish-brown wood is very fine grained, moderately light and very brittle. Single-leaf pinyon wood has little commercial use.
Arid mountain slopes, canyon sides, mesas and foothills with rapid evaporation, light precipitation and little humidity between 2,000 and 8,000 feet are single-leaf pinyon habitat. These trees are found throughout the Great Basin, NW and Central Arizona, the mountains of SE California and Baja California.
These specimens were photographed near Nevada Route 844 not far from Berlin Ichthyosaur State Park. P monophylla has many other common names including nut pine and one-leaf pine.