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Tree to 12 m, trunk short, contorted, often forked, 0.2–0.3 m dbh. Bark thin, smooth, greyish brown; in older trees smooth, thin, breaking into irregular plates divided by longitudinal and rarely horizontal fissures on lower trunk. Crown broad, open and irregular, with some young branches trailing along the ground. Branchlets long, slender, flexible, arching, drooping and ultimately pendulous, greyish brown to grey; vegetative buds inconspicuous, not resinous. Leaves in fascicles of three (to four), persisting for two to three years, in sparse tufts near the ends of branchlets, straight and rigid on pendulous shoots, drooping on stronger shoots, greyish green, triangular in cross-section, 5–12(–14) × 0.08–0.12 cm, apex acute. Fascicle sheaths to 1 cm long, slowly deciduous. Cataphylls 0.3–0.4 cm long, early deciduous. Male strobili purplish or yellowish, ovoid-oblong, 0.8–1 × 0.4–0.5 cm. Female cones lateral, not on ultimate branches, solitary or rarely in pairs; peduncles brittle, slender, straight or curved. Cones 5–10 × 3.5–6(–7) cm, green, ripening yellow-brown to orange-brown, mature in about 18 months; mature cones ovoid-oblong or cylindrical, sometimes irregular. Scales 60–80, opening partially or fully, thick, softly woody; apophysis irregularly domed, lustrous yellow- to orange-brown, occasionally with concentric rings due to irregular rainfall; umbo dorsal, grey with a minute prickle. Seeds golden-brown (infertile seeds paler), 11–13 mm; wings vestigial, remaining attached to the cone scales. Farjon & Styles 1997, Farjon et al. 1997, Farjon 2005a. Distribution MEXICO: Coahuila, Hidalgo, Querétaro, San Luis Potosí, northern Zacatecas. Habitat Slopes and ravines in arid and semi-arid mountains, between 1400 and 2300 m asl. USDA Hardiness Zone 9. Conservation status Lower Risk. Illustration Farjon & Styles 1997, Farjon 2005a; NT615. Cross-reference K231.
Pinus pinceana is another attractive pine that has great horticultural prospects, but as yet is little known in gardens. It forms a short, bushy tree of the usual pinyon sort but with a distinctly weeping habit. The needles are an attractive bright green, though young plants bear glaucous juvenile leaves for several years. In the wild it grows in very arid situations, with a selection of strongly xerophytic plants including Fero cactus, Opuntia and Agave, suggesting that it is suitable for dry sites (Gymnosperm Database 2007f). Gatherings have been made by several collectors, including Frankis 100 from Coahuila in 1991, and Gardner & Knees 5126 from Hidalgo in 1993, trees from both of which have been outhoused from Edinburgh. A first attempt at Tregrehan failed, probably because the seedlings were planted too young, but older plants have become established and are now about a metre high (T. Hudson, pers. comm. 2007).