Юго-западная белая сосна (Pinus strobiformis)

Species of conifer

Pinus strobiformis, commonly known as southwestern white pine, Mexican white pine or Chihuahua white pine, is a medium sized white pine tree whose native habitat is in southwestern United States and Mexico. It is typically a high elevation pine growing mixed with other conifers (a montane forest).

Pinus strobiformis, a member of the white pine group, Pinus subgenus Strobus, is a straight, slender tree growing to 100 ft (30 m) tall and 3 ft (1 m) in diameter. The bark is smooth and silvery gray on young trees, aging to furrowed and red brown or dark gray brown. The branches are spreading and ascending. Twigs are slender, pale red brown, aging to smooth gray or gray brown. Buds are ellipsoid, red brown, and resinous. Leaves (needles) are five per bundle (fascicle), sometimes four, spreading to ascending upcurved, 1.5 to 3.5 in (4–9 cm) long (rarely up to 4 in), 0.6 1.0 mm in diameter, straight, slightly twisted, pliant, dark green to blue green, and persist 3–5 years. The upper surface ('adaxial' facing toward the stem of the plant) is conspicuously whitened by narrow stomatal lines. The lower surfaces ('abaxial' facing away from the stem of the plant) are without evident stomatal lines. The margins are sharp, razorlike and entire to finely serrulate, apex narrowly acute to short subulate. Each fascicle has a deciduous sheath 0.5 to 0.75 in (1.5 2.0 cm) long which is shed early. The cones are very large, 6 to 20 in (16–50 cm) long and 3.5 to 4.5 in (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. It is a very drought tolerant tree but greater populations grow on moist and cool places living in association with Pinus hartwegii.