A tree attaining 100 ft or slightly more in the wild; trunk grey, smooth on young trees, becoming shallowly furrowed and reddish brown with age; terminal buds brown, resinous, about 1⁄2 in. long, the scales with free, acuminate tips. Young branchlets usually covered with a short, brown down. Leaves in fives, very slender, falling the third year, 4 to 7 in. long, three-sided, the outer side green, the two inner surfaces each with three or four white lines of stomata, margins toothed; leaf-sheaths 3⁄4 in. long, soon falling away. Cones 6 to 12 in. long, 1 to 21⁄2 in. wide before expanding, cylindrical, with a tapered, slightly curved apex; they are pendulous, shortly stalked, and borne in twos or threes, or sometimes singly; scales about 1 in. wide, with a blunt, resinous, sometimes reflexed apex, but the basal scales always strongly reflexed. Seeds with a relatively narrow wing 1 in. or even more long, the body of the seed about 3⁄8 in. long.
Native of Guatemala and of southern and central Mexico, from 8,000 to 10,000 ft, in sheltered valleys or on the slopes of the moister mountain ranges, where even in the dry season there is frequent low cloud and drizzle. It was introduced to Britain by Hartweg, who sent cones to the Horticultural Society from Guatemala in 1840. But the existing trees probably all derive from later introductions and some belong to the following variety:
var. veitchii Shaw P. veitchii Roezl, nom.; P. bonapartea Roezl ex Gard. Chron.; P. loudoniana Gord. – Body of seed relatively larger, about 1⁄2 in. long, wing shorter and relatively broader, about 1⁄2 in. long. Cones sometimes as long as 15 in., with scales 11⁄8 to 11⁄4 in. wide. According to Martinez there is the further difference that the scales are thicker and stronger than in the typical state of the species. This variety is apparently confined to central Mexico, where intermediate forms also occur (Martinez).
P. ayacahuite and the var. veitchii are both likely to vary in hardiness, according to provenance. The famous tree at Westonbirt is now decrepit and no longer bears cones, but at one time it coned freely and many seedlings were raised from it (some of which proved to be hybrid; see P. × holfordiana). This tree certainly belongs to the var. veitchii; Shaw, who saw cones from it in the Herbarium of the Arnold Arboretum, actually cites it in his description of var. veitchii. The statement by Elwes and Henry that var. veitchii is tender probably refers to the original introduction by Roezl (as P. veitchii).
Among the largest or oldest specimens of P. ayacahuite (some may be var. veitchii) are: Kew, pl. 1873, 54 × 31⁄2 ft (1974) and another, possibly a seedling of the Westonbirt tree, pl. 1904, 49 × 41⁄2 ft (1966); R.H.S. Pinetum, Wisley, Surrey, 62 × 71⁄4 ft (1969); Hergest Croft, Heref., pl. 1916, 60 × 6 ft (1968); Bicton, Devon, 88 × 71⁄2 ft and 78 × 83⁄4 ft (1968); Bodnant, Denb., pl. 1902, 64 × 103⁄4 ft and 71 × 101⁄2 ft (1974); Fota, Co. Cork, Eire, pl. 1902, 60 × 73⁄4 ft (1966).
The Westonbirt specimen of var. veitchii, mentioned above, has lost its top; it measured 62 × 63⁄4 ft in 1909 and is now 81⁄2 ft in girth (1971).
var. brachyptera Shaw P. strobiformis Engelm. – Seed about 1⁄2 in. long, the wing reduced to a mere rim or absent. Native of N. Mexico, commonest in the states of Coahuila and Durango. Probably not in cultivation, but worthy of introduction, as it should succeed in eastern England.