Pinus strobiformis
Pinus strobiformis, also known as Chihuahua white pine, is a medium-sized white pine tree endemic to western Mexico in the Sierra Madre Occidental mountain range. It is typically a high-elevation pine growing mixed with other conifers in montane forest. It was formerly considered conspecific with Pinus reflexa of the southwestern United States and Pinus stylesii of northeastern Mexico, but is now treated as distinct from these.
Description
Pinus strobiformis, a member of the white pine group, Pinus subgenus Strobus, is a straight, slender tree growing to tall and in diameter. The bark is smooth and silvery-grey on young trees, aging to furrowed and red-brown or dark grey-brown. The branches are spreading and ascending. The twigs are slender, pale red-brown, aging to smooth grey or grey-brown. The buds are ellipsoid, red-brown, and resinous. The leaves are five per bundle, spreading, 8–14 cm long, 0.6-1.0 mm in diameter, straight, slightly twisted, pliant, dark green to blue-green, and persist 3–5 years. The upper surfaces is conspicuously whitened by narrow stomatal lines. The lower surfaces are without evident stomatal lines. The margins are sharp, razorlike and finely serrulate, apex narrowly acute to short-subulate. Each fascicle has a deciduous sheath 1.5-2.0 cm long which is shed early.The cones are very large, 16–50 cm long and 9–11 cm broad, and have scales with a very characteristic prolonged and often recurved or S-shaped apex. The seeds are large, and with a very short wing; they are dispersed mainly by birds, particularly the Mexican jay.