Pinus ponderosa

Scientific name: Pinus ponderosa D.Douglas ex C.Lawson 1836

Synonyms: Pinus beardsleyi A.Murray bis, Pinus benthamiana Hartw., Pinus craigiana A.Murray bis, Pinus engelmannii Torr., Pinus nootkatensis Manetti ex Gordon, Pinus parryana Gordon, Pinus resinosa Torr., Pinus sinclairiana Carrière, Pinus washoensis H.Mason & Stockw.

Common names:Ponderosa pine, Western yellow pine

Description

Tree to 50(-75) m tall, with trunk to 2(-2.8) m in diameter. Bark bright yellowish brown to reddish brown, thick, in mature trees divided into large, roughly vertically rectangular, flat-topped, scaly plates by deep, dark furrows. Crown deep, cylindrical or tapering, with numerous thick, horizontal branches densely clothed with foliage. Twigs orange-brown to reddish brown, coarse, rough with bases of scale leaves, hairless. Buds 12-25 mm long, very resinous. Needles in bundles of two to four (or five), each needle (7-)10-25(-30) cm long, stiff and straight to slightly twisted, lasting (2-)4-6(-8) years, yellowish green to dark green, sometimes a little waxy. Individual needles with inconspicuous lines of stomates on both the inner and outer faces, and 2(-10) resin canals midway between the outer surface and the two-stranded midvein t the corners and under both faces. Sheath 15-30 mm long at first, the lower 10-15 mm persisting and falling with the bundle. Pollen cones 15-35 mm long, yellowish brown or red. Seed cones 5-15 cm long, egg-shaped to almost spherical, sometimes slightly asymmetrical, with 75-120 seed scales, green before maturity, ripening yellowish brown, opening widely to release the seeds and soon falling off the short, thick stalk, leaving a few basal scales behind. Seed scales paddle-shaped to fairly rectangular, the exposed face horizontally diamond-shaped, crossed by a ridge topped by a prominent pyramidal umbo ending in a strong, sharp prickle. Seed body (3-)5-7(-9) mm long, the easily detachable wing 12-20(-25) mm longer.

Widely but discontinuously distributed across western North America from north-central Nebraska to southern British Columbia south to southern California, northern Durango and western Tamaulipas (Mexico). Forming pure, open forests on dry soils or mixed with hardwoods and other pines and conifers; 0-3,000 m.

Conservation Status

Red List Category & Criteria: Least Concern

(Pinus ponderosa is one of the most common pines in the Rocky Mountains of the USA and is therefore assessed as Least Concern)

References

Farjon, A. (2010). A Handbook of the World's Conifers. Koninklijke Brill, Leiden.

Eckenwalder, J.E. (2009) Conifers of the World: The Complete Reference. Timber Press, Portland.

IUCN Red List of Threatened Species, International Union for Conservation of Nature and Natural Resources. Cambridge, UK /Gland, Switzerland

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