Jeffrey Pine

Jeffrey Pine
A stand of east side Jeffrey Pine growing on volcanic table lands south of Mono Lake, Ca.
Conservation status
Least Concern (IUCN 2.3)[1]
Scientific classification
Kingdom:	Plantae
Division:	Pinophyta
Class:	Pinopsida
Order:	Pinales
Family:	Pinaceae
Genus:	Pinus
Subgenus:	Pinus
Species:	P. jeffreyi
Binomial name
Pinus jeffreyi Balf.

Jeffrey Pine (Pinus jeffreyi), named in honor of its documenter John Jeffrey, is a North American pine related to Ponderosa Pine. It 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 1500-2100 m altitude, and at 1800-2900 m in the south of its range.^[2]

The cone of a Jeffrey pine, showing the distinctive inward-pointing barbs.

The Jeffrey Pine is a large tree, reaching 25-40 m tall, rarely up to 53 m tall, though smaller when growing at or near tree line.^[2] The leaves are needle-like, in bundles of three, stout, glaucous gray-green, 12-23 cm long. The cones are 12-24 cm long, dark purple when immature, ripening pale brown, with thinly woody scales bearing a short, sharp inward-pointing barb. The seeds are 10-12 mm long, with a large (15-25 mm) wing.

It may be distinguished from Ponderosa Pine by the needles, which are glaucous, less bright green than those of Ponderosa Pine, and the stouter, heavier cones with larger seeds and inward-pointing barbs.^[3] Jeffrey Pine is also very distinct from Ponderosa Pine in its resin scent, variously described as reminiscent of vanilla, lemon, pineapple, violets, or apples;^[4] 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. Full-grown Jeffrey Pine is easily distinguished from Ponderosa Pine by the smaller scales of bark, as compared to the very large plates of more reddish-colored Ponderosa bark.

Jeffrey Pine is tolerant of serpentine soils, and is often dominant in these conditions, even on dry sites at fairly low altitude.^[2] On other soils, it only becomes dominant at higher altitudes where the usually faster-growing Ponderosa Pine does not thrive.

Uses

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.

Jeffrey pine in the Siskiyou Mountains of northwest California, growing on serpentine.

Young Jeffrey Pine at Stanislaus
National Forest, California.

References

External links

• Media related to Pinus jeffreyi at Wikimedia Commons