Leaves are mostly single, with a small proportion of two-needled fascicles. This leaf character is due to the abortion of one of the original two-needle primordia at a very early stage. The pale green leaves are three to five centimeters long, with dark green lines. They are stiff, prickly and curved toward the branch with deciduous sheaths. The pinyon pine is noteworthy for being the only pine with single needles that end in a spike.
Reproductive maturity comes at a relatively old age, about twenty-five years.
Unlike most pines, pinyon pine seeds are wingless. P. monophylla seeds are almost one inch long and have a high fat content. It is from these seeds, in Spanish called pinyons, that the tree receives its name. These nutritious seeds, highly sought after by all types of wildlife, were important historically to the Native Americans. Pinyon pines are the source of the largest wild seed crop in the United States.