Pinus monophylla, the single-leaf pinyon, (alternatively spelled piñon) is a pine in the pinyon pine group, native to North America. The range is in southernmost Idaho, western Utah, Arizona, southwest New Mexico, Nevada, eastern and southern California and northern Baja California.
It occurs at moderate altitudes from 1,200 to 2,300 m (3,900 to 7,500 ft), rarely as low as 950 m (3,120 ft) and as high as 2,900 m (9,500 ft). It is widespread and often abundant in this region, forming extensive open woodlands, often mixed with junipers in the Pinyon-juniper woodland plant community. Single-leaf pinyon is the world's only one-needled pine.
Pinus monophylla is a small to medium size tree, reaching 10â20 m (33â66 ft) tall and with a trunk diameter of up to 80 cm (31 1â2 in) rarely more. The bark is irregularly furrowed and scaly. The leaves ('needles') are, uniquely for a pine, usually single (not two or more in a fascicle, though trees with needles in pairs are found occasionally), stout, 4â6 cm (1 1â2â2 1â4 in) long, and grey-green to strongly glaucous 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, 4.5â8 cm (1 3â4â3 1â8 in) long and broad when closed, green at first, ripening yellow-buff when 18â20 months old, with only a small number of very thick scales, typically 8â20 fertile scales. The cones thus grow over a two-year (26-month) cycle, so that newer green and older, seed-bearing or open brown cones are on the tree at the same time (see image at left).