Ponderosa Pine

(Pinus ponderosa)

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Color Photographs: © by and courtesy of Charles Webber, California Academy of Sciences

Ponderosa Pine (Pinus ponderosa)

Identifying Characters: Ponderosa Pine is very widespread in the western United States and geographically variable.The reddish-brown bark of mature trees, broken into large, flat scaly plates is usually distinctive for the species.

Similar Species: Because of its geographically variability Ponderosa Pine might be mistaken for a number of different species in different localities.The reddish-brown bark of mature trees, broken into large, flat scaly plates is usually distinctive for the species.

Measurements: Geographically variable in size, ranging from 60 to 130 feet in height and 2 to 4 feet in diameter at maturity.

Cones: Cones geographically variable in size ranging from 2 to 6 inches in length, longest in the variety ponderosa; conical to ovate in shape, stalk nearly absent; cone scales thickened at the apex, with a small apical spine, and with a raised keel.

Needles: Needles generally 4 to 8 inches long, thick, stiff, and dark green; number of needles in a bundle geographically variable (3 in variety ponderosa, 2 in variety scopulorum, and 5 (sometimes less) in variety arizonica).

Bark: Bark on mature trees reddish-brown and broken into large, flat, scaly plates; bark on young trees black-brown, rough, and broken into ridges.

Native Range: The range of Ponderosa Pine extends from southern Canada into Mexico, and from the Plains States of Nebraska and Oklahoma to the Pacific Coast.

Pacific Ponderosa Pine (var. ponderosa) ranges from latitude 52° N. in the Fraser River drainage of southern British Columbia, south through the mountains of Washington, Oregon, and California, to latitude 33° N. near San Diego. In the northeast part of its range it extends east of the Continental Divide to longitude 110° W. in Montana, and south to the Snake River Plain, in Idaho.

Rocky Mountain Ponderosa Pine (var. scopulorum) extends east of the Continental Divide from latitude 48° N. in north-central Montana, southeasterly into North and South Dakota, eastern Wyoming, and as far east as north-central Nebraska. Within this area, ponderosa pine grows on the discontinuous mountains, plateaus, canyons, and breaks of the plains, with the most extensive stands found in the Black Hills of South Dakota and Wyoming. South of Wyoming, Rocky Mountain ponderosa pine extends south on both sides of the Continental Divide, west to Arizona, and the eastern edge of the Great Basin in Nevada, east to Texas west of the Pecos River, New Mexico, extreme northwestern Oklahoma, Colorado, and northern Mexico. Within this wide range, ponderosa pine is absent from a large area that includes southwestern Montana, western Wyoming, southern Idaho, and part of the Great Basin. A possible explanation for the absence is that the distribution of rainfall during the summer months prevents seedling establishment except at higher elevations, where the species has little tolerance for the shorter growing season.

Arizona Pine (var. arizonica) is found primarily in the mountains of extreme southwestern New Mexico, southeastern Arizona, and northern Mexico. (Silvics of North America. 1990. Agriculture Handbook 654.)

Habitat: Widely distributed in western North America, most often occurring in extensive pure stands. The species is commonest between 4000 and 8000 feet.

NOTES: Ponderosa Pine is possibly the most widespread pine in western North America and often forms extensive nearly pure stands. It is a very important and valuable timber tree.