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Pinus jeffreyi, also known as Jeffrey pine, Jeffrey's pine, yellow pine and black pine, is a Pinus tree. It is mainly found in California, but also in the westernmost part of Nevada, southwestern Oregon, and northern Baja California.Safford, H.D. 2013. Natural Range of Variation (NRV) for yellow pine and mixed conifer forests in the bioregional assessment area, including the Sierra Nevada, southern Cascades, and Modoc and Inyo National Forests. Unpublished report. USDA Forest Service, Pacific Southwest Region, Vallejo, CA, [1] It is named in honor of its botanist documenter John Jeffrey.
Pinus jeffreyi is closely related to Pinus ponderosa (ponderosa pine) and is similar in appearance. One way to distinguish between them is by their cones. Each has barbs at the end of the scales. The sharp P. jeffreyi cone scale barbs point inward, so the cone feels smooth to the palm of one's hand when rubbed down the cone. Pinus ponderosa cone scale barbs point outward, so feel sharp and prickly to the palm of one's hands. The memory device of 'gentle Jeffrey' and 'prickly ponderosa' can be used to differentiate between the species. Another distinguishing characteristic is that the needles of P. jeffreyi are glaucous, less bright green than those of P. ponderosa, and by the stouter, heavier cones with larger seeds and inward-pointing barbs. (2025). 9781402738753, Sterling. ISBN 9781402738753 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.
The scent of P. jeffreyi is variously described as reminiscent of vanilla, lemon, pineapple, violets, apple, 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 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 .
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 and is often dominant in these conditions, even on dry sites at fairly low altitudes.
Mammals and birds collect the seeds.
As it mainly consists of n-heptane, P. jeffreyi resin is a poor source of turpentine. 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.
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.
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. The exceptional purity of distilled from P. jeffreyi resin led to being selected as the zero point on the octane rating scale of petrol.
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