The single-leaf piñon is a pine in the piñon pine group which grows in the San Bernardino Mountains, the San Gogonio Wilderness and the eastern San Gabriel Mountains in San Bernardino County. Known scientifically as Pinus monophylla, it is
native to the United States and northwest Baja California. Within California it is found in the Sierras, the Transverse Range, and Peninsular Range. It occurs at moderate altitudes from 3,900 feet to 7,500 feet, rarely as low as 3,100 feet and as high as 9,500 feet, in the most arid areas occupied by any pine in California. It is widespread and often abundant in this region, forming extensive open woodlands, often mixed with junipers. It is a small to medium size tree, reaching 32 to 65 feet tall tall and with a trunk diameter of up to 32 inches, rarely more. However, it is very slow growing, reaching only 3 feet in seven years.The bark is irregularly furrowed and scaly. It is the world’s only 1-needled pine as the leaves, or needles, are usually single, though trees with needles in pairs are found occasionally. An isolated population of single-leaf piñon trees in the Mojave Desert’s New York Mountains, which lie within the Mojave National Preserve, has needles mostly in pairs and was previously thought to be Colorado piñons. They have recently been shown to be a two-needled variant of single-leaf piñon based upon a genetic examination. The needles are stout, 1.6 inches to 2.4 inches long, and grey-green to strongly waxy pale blue-green, with pores or a slit over the whole needle surface, and on both inner and outer surfaces of paired needles. The cones are acute-globose, the largest of the true piñons, 1.8 inches to 3.2 inches long and broad when closed, green at first, ripening yellow-buff when 18-to-20 months old, with only a small number of very thick scales, typically 8-20 fertile scales. The cones open to 2.4 inches to 3.6 inches broad when mature, holding the seeds on the scales after opening. The seeds are 11-16 millimeter long, with a thin shell, a white endosperm, and a vestigial 1-2 millimeter wing; they are dispersed by the piñon jay, which plucks the seeds out of the open cones. The jay, which uses the seeds as a food resource, stores many of the seeds for later use by burying them. Some of these stored seeds are not used and are able to grow into new trees. Indeed, piñon seeds will rarely germinate in the wild unless they are cached by jays or other animals. The seeds, called pine nuts, are also harvested and eaten by people. Indians of the Great Basin region commonly ate them. The Shoshoni name for the plant is ai’-go-û-pi.
The butterflies likely hosted by the single-leaf pinon include the pine white butterfly, Neophasia menapial and the western pine elfin butterfly, Callophrys eryphonl. Moths hosted by the single-leaf pinon include the polyphemus moth, Antheraea polyphemus; the brown-lined looper moth, Neoalcis californiaria; the speckled green fruitworm moth Orthosia hibisci; the Red Girdle Moth, Caripeta aequaliarial; the brown woodling, Egira perlubens; the silver-spotted tiger moth, Lophocampa argentata; the manto tussock moth, Orgyia antiqua; the sulphur moth, Hesperumia sulphuraria; the western carpet, Melanolophia imitata; the mottled gray carpet, Cladara limitaria, the skunk moth, Polix coloradella, the common gray, Anavitrinella pampinaria; the gray swordgrass moth, Xylena cineritia; the birch angle, Macaria notata; the spruce coneworm, Dioryctria reniculelloides; the sequoia pitch moth, Synanthedon sequoiae; the Nantucket pine tip moth, Rhyacionia frustrana; the pine needle sheathminer, Zelleria haimbachi; the variable girdle moth; Enypia venata; the pale-marked angle, Macaria signaria; the sharp-lined yellow, Sicya macularia; the Florida pink scavanger caterpillar, Pyroderces badia; the ponderosa pineconeworm moth, Dioryctria auranticella; the reticulated decantha moth, Decantha boreasella; the ragweed borer, Epiblema strenuana; the mountain girdle moth, Enypia griseata; the pale beauty, Campaea perlata; Packard’s girdle moth, Enypia packardata; the white triangle tortrix, Clepsis persicana; the fall webworm; Hyphantria cunea; the pandora pinemoth, Coloradia pandora; the lodgepole pine needle-miner, Coleotechnites milleri; the orange tortrix moth, Argyrotaenia franciscana; the Zenophleps lignicolorata; the Sabulodes edwardsata;  the Phaeoura mexicanaria; Dyar’s looper moth, Gabriola dyari; the Spodolepis substriataria; the Glena nigricaria; the Eupithecia ornata; the false pinion moth, Litholomia napaea; the Euxoa auripennis; the Eupithecia longipalpata; the Macaria adonis; the Cochisea sonomensis; the Lophocampa ingens; the Hydriomena speciosata; the Nepytia umbrosaria; the tamarack looper; Eupithecia misturata; the Tetracis pallulata; the Stenoporpia pulmonaria; the Retinia picicolana; the Dioryctria muricativorella; the Hydriomena nevadae; the Gloveria arizonensis; the Tolype lowriei; the Stenoporpia excelsaria; the Panthea gigantea; the Chionodes retiniella; the Retinia sabiniana; the Decantha stonda; the Chionodes abella; the Lithophane ponderosa; the Thallophaga hyperborea; the Elatobia carbonella; Behr’s Pero Moth, Pero behrensaria; the Douglas fir pitch moth; Synanthedon novaroensis; the clandestine cart, Spaelotis clandestina; the Douglas fir tussock moth, Orgyia pseudotsugata; the larch pug, Eupithecia annulata; the Coloradia velda; the red-striped needleworm moth, Epinotia radicana; the western conifer looper, Syngrapha celsa; the ponderosa pine seedworm moth, Cydia piperana; the Chionodes sabinianae; the Lithophane atara; the Xestia mustelina; the Laetilia zamacrella; the sugar pine tortrix moth, Choristoneura lambertiana; the Holcocera iceryaeella; the Euxoa extranea; the furious varpet moth, Hydriomena irata; the Egira variabilis; the Epinotia hopkinsana; the Papestra quadrata; and the Dioryctria pentictonella.

From https://calscape.org, Wikipedia