The Single-leaf Pinyon (Pinus monophylla) is a pine in the pinyon pine group, native to the United States and northwest Baja, Mexico. Within California it is found in the Sierras, the Transverse Range, and Peninsular Range. It occurs at moderate altitudes from 1200-2300 meter, rarely as low as 950 meter and as high as 2900 meter, 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 10-20 meter tall and with a trunk diameter of up to 80 centimeter, rarely more. However, it is very slow growing, reaching only 3 ft. in seven years.The bark is irregularly furrowed and scaly. It is the world's only 1-needled pine; the leaves ('needles') are usually single (though trees with needles in pairs are found occasionally), stout, 4-6 centimeter long, and grey-green to strongly waxy pale blue-green, with stomata 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 pinyons, 4.5-8 centimeter long and broad when closed, green at first, ripening yellow-buff when 18-20 months old, with only a small number of very thick scales, typically 8-20 fertile scales. The cones open to 6-9 centimeter 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 Pinyon 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, Pinyon seeds will rarely germinate in the wild unless they are cached by jays or other animals. The seeds (pine nuts) are also harvested and eaten by people.