Pinus jeffreyi is a species of evergreen needleleaf coniferous plants (in the Pinaceae or Pine family), native to westernmost North America, between Oregon and Baja California. It is a large tree that can attain 50 metres, though more commonly about 30 metres. It has a narrow shape and a straight trunk, whose bark is yellow-brown or grey, divided by deep furrows into plates. The tree bears needles in bunches of three, up to 25 cm in length, yellow-green and tending to spread upwards. Its seed cones are large, up to 30 cm long. Pinus jeffreyi is found in the mountains of its native range, between 1500 and 3000 metres altitude, exceptionally to almost 4000 metres. In such environments it grows slowly yet more readily than other species, owing to its tolerance of cold and poor soil, and can live for several hundred years.

Pinus jeffreyi is closely related and quite similar to Pinus ponderosa (also present in Whiteknights Park). Of these two, Pinus jeffreyi grows at higher altitude, its needles are of a darker colour, and its cones are larger and pricklier. The two species yield relatively low-density timber of indistinguishable properties, suitable for construction. They differ in the chemical composition and scent of their resin (a thick, sticky substance made by the cambium layer, not far inside the trunk, if the bark is damaged). Pinus jeffreyi resin contains heptane, which is used as an organic solvent and smells like petrol, of which it is a minor constituent.

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