| Pinus jeffreyi|
|A stand of east side Jeffrey pine growing on volcanic table lands south of Mono Lake, Ca.|
| Pinus jeffreyi|
Distribution and habitat
Pinus jeffreyi occurs from southwest Oregon south through much of California (mainly in the Sierra Nevada), to northern Baja California in Mexico. It is a high altitude species; in the north of its range, it grows widely at 1,500 to 2,100 m (4,900 to 6,900 ft) altitude, and at 1,800 to 2,900 m (5,900 to 9,500 ft) in the south of its range.
Jeffrey pine is tolerant of serpentine soils, and is often dominant in these conditions, even on dry sites at fairly low altitude. On other soils, it only becomes dominant at higher altitudes where the usually faster-growing ponderosa pine does not thrive.
The Jeffrey pine, Pinus jeffreyi, is a large coniferous evergreen tree, reaching 25 to 40 m (82 to 131 ft) tall, rarely up to 53 m (174 ft) tall, though smaller when growing at or near tree line. The leaves are needle-like, in bundles of three, stout, glaucous gray-green, 12 to 23 cm (4.7 to 9.1 in) long. The cones are 12 to 24 cm (4.7 to 9.4 in) long, dark purple when immature, ripening pale brown, with thinly woody scales bearing a short, sharp inward-pointing barb. The seeds are 10 to 12 mm (0.39 to 0.47 in) long, with a large (15 to 25 mm (0.59 to 0.98 in)) wing.
The Jeffrey pine may be distinguished from the closely related ponderosa pine by the needles (image at left), which are glaucous, less bright green than those of ponderosa pine, and by the stouter, heavier cones with larger seeds and inward-pointing barbs (see image lower left). Jeffrey pine is also very distinct from ponderosa pine in its resin scent, variously described as reminiscent of vanilla, lemon, pineapple, violets, apple; and, quite commonly, butterscotch; compared to the turpentine or odorless scent of ponderosa pine. This may be tested by breaking a small shoot or some needles, or by sampling the scent of the resin in between the plates of the bark. This difference in scent is related to the very unusual composition of the resin, with the volatile component made up almost entirely of pure n-heptane. Jeffrey pine can be distinguished from ponderosa pine by the smaller scales of bark as compared to the larger plates of more reddish-colored Ponderosa bark.
Jeffrey pine wood is similar to ponderosa pine wood, and is used for the same purposes. The exceptional purity of n-heptane distilled from Jeffrey pine resin led to n-heptane being selected as the zero point on the octane rating scale of petrol.
As n-heptane is explosive when ignited, Jeffrey pine resin cannot be used to make turpentine. Before Jeffrey pine was distinguished from ponderosa pine as a distinct species in 1853, resin distillers operating in its range suffered a number of 'inexplicable' explosions during distillation, now known to have been caused by the unwitting use of Jeffrey pine resin.
Long, glaucous needles
The cone of Pinus jeffreyi, showing the distinctive inward-pointing barbs
Base of Jeffrey pine, showing bark plates
- , Bulletin No. 95, pp. 17-20 retrieved Nov. 13, 2011
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