Mexican Pinyon

(Pinus cembroides)

Color Photographs: © by and courtesy of Stephen J. Baskouf

Color Photograph: U.S. National Parks Service

Mexican Pinyon (Pinus cembroides)

Identifying Characters: The deciduous bundle sheath on old needle bundles and the dry, pinyon-juniper habitat of this species will identify it as a pinyon. The edges of the needles are finely toothed and needle bundles contain 3 (rarely 2) needles.

Similar Species: The edges of the needles are finely toothed in Mexican Pinyon, but smooth in Pinyon (Pinus edulis). The number of needles per bundle in Mexican Pinyon is usually 3 (but rarely 2) in contrast to 2 needles in Pinyon (rarely 3). Single-leaf Pinyon contains 1 needle (rarely 2) per bundle and Four-leaf Pinyon contains 4 needles per bundle.

Measurements: Mexican Pinyon is a small, often shruby tree between 16 and 20 feet in height and 1 foot in diameter.

Cones: Cones are 1 to 2 inches long, ovoid or round, nearly sessile on the branch, and commonly covered with resin; cone scales thick, slightly quadrate in appearance, with a minute apical spine.

Needles: Needles are in bundles of 3, although occasional bundles of 2 occur; sheath shed after the first year; needles are between 1 and 2 inches in length; needles slender, flexible, green, with white lines on all surfaces or only on the ventral surfaces.

Bark: Bark light gray and smooth in younger trees, becoming darker gray or slightly reddish-brown and furrowed into scaly plates in older individuals.

Native Range: Mexican Pinyon is primarily a Mexican species reaching the United States in south-central and Trans-Pecos Texas, and stretching westward into extreme southern New Mexico and southeastern Arizona.

Habitat: This species occurs on dry, rocky slopes of mesas, plateaus, and the lower reaches of mountains. It is commonly found in association with various species of juniper and evergreen oaks.

Notes: Mexican Pinyon is the chief source of Pinyon Nuts in Mexico, but is too rare in the United States to be a commercial crop. Two varieties of Mexican Pinyon are sometimes treated as distinct species.

The systematics of the Pinyon Pines are currently fluid with disagreement between authorities on specific limits. This is particularly true of Mexican Pinyon. Two isolates of Mexican Pinyon are considered separate species by some experts. Pinus remota Bailey and Hawksworth consists of a series of isolated populations in western Texas and adjacent northern Mexico. It is separated from Mexican Pinyon (Pinus cembroides) by a thinner seed shell and an earlier shedding of the sheath of the needle bundles. The second possible species is Pinus discolor Bailey and Hawksworth. Pinus discolor occurs, reportedly together with cembroides, in southern Arizona, New Mexico, and adjacent northern Mexico and is based on a number of small differences between two and a reported absence of hybrids between the two "species". Pinus discolor is sometimes listed as a synonym of the Mexican species Pinus johannis, itself sometimes considered a synonym of cembroides.