A bushy tree usually 15 to 20 ft high, sometimes 40 or 50 ft, the young branches slender, glaucous. Leaves mostly in threes, sometimes in pairs, persisting for about three years, 1 to 2 in. long, dark green; in each cluster the inner faces of the leaves are pressed together, especially when young; margins not toothed; leaf-sheath at first 1⁄4 to 3⁄8 in. long, the scales afterwards becoming reflexed and forming a rosette round the base of each cluster. Cones roundish, egg-shaped, 11⁄2 to 2 in. long, 1 to 11⁄2 in. wide, with very few scales. Seeds 1⁄2 in. long, edible.
Native of Mexico (including northern Baja California) and of bordering parts of Arizona, New Mexico, and Texas; introduced by Hartweg in 1839, but very rare in collections. The seeds are sold in Mexican markets as ‘piñones’. The nut pines of the south-western USA are now included in P. cembroides as varieties by most botanists. These are:
var. edulis (Engelm.) Voss P. edulis Engelm. – Leaves chiefly in pairs instead of threes and rather thicker; otherwise scarcely differing from typical P. cembroides. Native mainly of Colorado, Utah, Arizona, and New Mexico, but also occurring in northern Mexico. It is a pleasing small tree of neat dense habit, but very rare in gardens.
var. monophylla (Torr. & Frem.) Voss P. monophylla Torr. & Frem. Singleleaf Nut Pine. – Leaves solitary and terete (circular in cross-section), or occasionally in pairs and then semi-terete. It has a more westerly distribution than var. edulis, mainly in Utah, Arizona, Nevada, and S. California, and often forms pure stands of considerable extent. It is one of the main sources of pinyons (pine nuts). The best known and largest specimen in Britain grows in the University Botanic Garden, Cambridge; planted shortly before 1900, it measures 33 × 31⁄2 ft (1969); when young it gained an average of 8 in. in height per annum (Journ. R.H.S., Vol. 41 (1915), p. 7 and fig. 8). There are smaller trees at Edinburgh and Kew. This pine deserves to be more widely planted, especially in the drier parts of the country.
var. parryana (Engelm.) Voss P. parryana Engelm., not Gord.; P. quadrifolia Sudw. Fourleaf Nut Pine. – Leaves mostly in fours. Native of S. California, extending into the Mexican state of Baja California. Probably not in cultivation. The P. parryana of Gordon is P. ponderosa.
P. nelsonii Shaw – A small tree with pale glaucous or whitish shoots. Leaves in threes, usually adhering and apparently single in wild plants, slender, up to 21⁄2 in. long (occasionally longer), three-sided, light green on the outer side; sheaths persistent, about 1⁄4 in. long, not reduced to a rosette. Cones cylindrical or oblong-ovoid, up to 5 in. long, pendulous from the downward curving of the stout peduncle, which is 1 to 2 in. long; scales relatively few, the exposed part rhomboidal, the transverse diameter much the larger, with wide, prominent umbos; seeds large, wingless, edible (Gard. Chron., Vol. 36 (1904), p. 122, fig. 49).
Native of N.E. Mexico. A tree at Kew, planted in 1910, is considered to belong to this species. It measures 32 × 21⁄4 ft (1969).