Pinus jeffreyi

Pinus jeffreyi is a large coniferous evergreen tree, reaching tall, rarely up to tall, though smaller when growing at or near tree line. The cones are long, Pinus jeffreyi can be somewhat distinguished from P. ponderosa by the relatively smaller scales of reddish-brown bark as compared to the larger plates of orangish ponderosa bark. and, quite commonly, butterscotch. This scent may be sampled by breaking off a shoot or some needles, or by simply smelling the resin's scent in between the plates of the bark. This scent is related to the very unusual composition of the resin, with the volatile component made up almost entirely of pure n-heptane. It is because of this peculiarity that the trees are sometimes known as gasoline trees. Easy availability of this hydrocarbon in pure form made it the basis of the modern octane rating in the late 1920s. The largest specimen, by trunk volume, is the Eureka Valley Giant, in the Stanislaus National Forest. Its trunk contains of wood, is tall, with a diameter of . == Taxonomy ==

Pinus jeffreyi is named for its discoverer, Scottish botanist John Jeffrey, who encountered it in 1852 near Mount Shasta. Pinus is Latin for pine. ==Distribution and habitat==

Pinus jeffreyi occurs from southwest Oregon south through much of California (mainly on the eastern side of 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 altitude, and at in the south of its range. Pinus jeffreyi is more stress tolerant than P. ponderosa. At higher elevations, on poorer soils, in colder climates, and in drier climates, P. jeffreyi replaces P. ponderosa as the dominant tree. Pinus jeffreyi is also tolerant of serpentine soils and is often dominant in these conditions, even on dry sites at fairly low altitudes. of northwest California, growing on serpentine ==Ecology==

Pinus jeffreyi can hybridize with P. ponderosa and the Coulter pine, however this occurrence is rare due to the fact that the pines release pollen at different times of the year. Mammals and birds collect the seeds. ==Uses==

Pinus jeffreyi wood is similar to ponderosa pine wood, and is used for the same purposes. Crystallized sap of P. jeffreyi has been eaten as candy. Before Pinus jeffreyi 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. == See also ==