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Tree to 40 m, trunk straight and erect, 1–1.5 m dbh. Bark thin, smooth, silvery grey at first, in older trees thick, rough, scaly, dark brown to grey, with long shallow vertical fissures. Crown initially conical, becoming open and irregular with long horizontal branches in mature trees. Branchlets slender, smooth, finely pubescent at first, becoming glabrous; vegetative buds reddish brown, resinous. Leaves in fascicles of five, in sparse tufts near the ends of ultimate branches, persisting for two to three years, straight or pendent, often slightly twisted, light green on the outer face, glaucous bluish white on the inner faces, triangular in cross-section, (5–)7–13 × 0.06–0.08(–0.1) cm, margins serrulate, apex acute. Fascicle sheaths 1–1.5 cm long, orange-brown, rapidly disintegrating. Cataphylls 0.4–0.5 cm long, brown. Male strobili yellow to orange-brown, ovoid-oblong to cylindrical, 0.5–0.8 cm long. Female cones subterminal and axillary, solitary or in pairs or in whorls of three; peduncles long and slender, 1.5–4.5 cm long, erect then pendulous, falling with the cone. Cones (6–)8–15(–25) × 2–3 cm closed, green to dark brown, mature in about 15–18 months; mature cones variable, mainly cylindrical, occasionally slightly curved. Scales 50–90, opening obliquely; scales thin, straight, fragile; apophysis usually rather resinous, mid-brown; umbo terminal, greyish brown, resinous. Seeds dark grey-brown, 0.7–0.9 × 0.4–0.5 cm; wings adnate, 2–3 × 0.6–0.9 cm, light brown with dark streaks. Andresen 1966, Farjon & Styles 1997, Farjon et al. 1997, Farjon 2005a. Distribution GUATEMALA; MEXICO: Chiapas, Guerrero, Oaxaca, eastern Puebla, Tabasco, Veracruz. Habitat Subtropical or warm temperate montane forests between 500 and 2200 m asl. USDA Hardiness Zone 9–10. Conservation status Vulnerable. Illustration Farjon & Styles 1997. Cross-references B242, K238.
Pinus chiapensis was first described by Martínez (1940) as a variety of P. strobus, and is still regarded as such by some (Farjon 2001, 2005a). Although few morphological foliage characters distinguish P. chiapensis from P. strobus, it is very distinct genetically, sharing no alleles with P. strobus and forming a distinct clade of its own, sister to two clades of American and Asian species (Liston et al. 2003, Syring et al. 2007). A few vegetative characters help identification. In P. chiapensis, the serrations on the leaf margins are larger, and there are fewer per unit length than in P. strobus. The proximal cone scales of P. chiapensis are straight, as in P. peuce and most other Eurasian white pines, while in P. strobus and P. monticola they are recurved.
Most white pines are attractive, and this Mexican species is quite as beautiful as any other. It has been collected in Veracruz (Gardner & Knees 5377, in 1993), from which source trees are established at Benmore and elsewhere, but it is not commonly grown. Despite its southerly and low-altitude distribution it seems to be hardy in Britain but its wider hardiness is unknown, and it is presumably subject to the same fungal and pest problems that plague P. strobus. It has been investigated for use as a tropical plantation species (Dvorak et al. 2000).