The currently accepted scientific name of singleleaf pinyon is Pinus monophylla Torr. & Frem. (Pinaceae) [92,103,142,232]. Subgenus Strobus, section Parrya, subsection Cembroides of Pinus [120].

Singleleaf pinyon has a large area of distribution and, therefore, probably a large degree of genetic variation [120]. It is the predominant tree species in the isolated mountain ranges of the Great Basin, ranging from southern Idaho, western Utah and northwestern Arizona, through most of Nevada (it's Nevada's state tree) and eastern and central California to northern Baja California [56,92,120,133,142]. There is about 2.5 billion ft3 of singleleaf pinyon in Nevada, and about 5 billion ft3 in Utah [162]. It is also found in the Mojave Desert borderlands of southern California and in small, fragmented populations in a belt across Arizona south of the Mogollon Rim into southwestern New Mexico [121,122].

Mature singleleaf pinyon is typically a short tree (20-40 feet (6-12 m) tall), with a rounded to flat-topped crown and multiple, upswept branches due to lack of self-pruning. The needles of singleleaf pinyon are solitary, rigid, and 1 to 1.4 inches (2.5-3.5 cm) long. The single needle (leaf) is unique among pines of the world [121]. Singleleaf pinyon needles are long-lived (5-12 years) [83,139]. Their longevity is considered an extreme expression of "evergreenness," giving the tree the ability to conserve nutrients to take advantage of short favorable conditions within a generally unfavorable period [139]. Singleleaf pinyon bears ovulate cones with thick scales. Cones bear large, heavy, moderately thin-shelled, edible, wingless seeds [137,211,232].  Singleleaf pinyon is long- lived. On fire-safe sites, large trees can monopolize site resources over a life span of 350 years or more [63]. Dominant pinyons are often 400 years old and have been known to reach 800 to 1000 years [105,174]. Mature singleleaf pinyon trees (over 200 years) are relatively uncommon [21,98].

Wood of singleleaf pinyon is used primarily for fuel wood and fence posts [95,115].
Pinyon-juniper woodlands provide shelter and forage for numerous species of wildlife such as pinyon mice and woodrats [142,143,157,182]. These forests have value as habitat for several large mammals such as mule deer, white-tailed deer, pronghorn, desert bighorn sheep, elk, wild horses, mountain lions, and bears [143,157,182,192,206]. Gray foxes, bobcats, coyotes, weasels, skunks, badgers, and ringtails search for prey here [182,248]. Many species of birds [4,20,54,143,171,229] and reptiles [157] find food and shelter here. Pinyon mice, deer mice, woodrats, squirrels, chipmunks, deer, black bears, and desert bighorn sheep eat singleleaf pinyon seeds [23]. Many of these animals cache seeds for winter use and are critical for regeneration of singleleaf pinyon [35,123,180,211]. Although it is not favored, mule deer eat pinyon foliage [121,124], using the foliage moderately in winter, spring, and summer [117]. Cows may feed on pinyon in the winter, and it is thought that this can cause them to abort [121]. The inner bark is a major food of porcupines, and is also eaten by squirrels, raccoons, rabbits, ringtails, coyotes, and gray foxes [182], as well as the larvae of the mountain pine beetle and the fungus causing pinyon blister rust [121]. Limbs are attacked by pinyon dwarf-mistletoe (Arceuthobium divaricatum). The pitch is a staple food of pitch midges and is used by Dianthidium bees to build their nests.
The seed or "nut" of singleleaf pinyon has a lower fat content than that of Colorado pinyon, giving it a more starchy or mealy taste by comparison [134