Southwestern White Pine (Pinus strobiformis)
Description
Pinus strobiformis, a member of the white pine group, Pinus subgenus Strobus, is a straight, slender tree growing to 30 m tall and 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, 4-9 cm long (rarely 10), 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 1.5-2.0 cm long which is shed early.
Taxonomic tree
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Domain: Eukarya
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Kingdom: Plantae
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Phylum: Coniferophyta
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Class: Pinopsida
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Order: Pinales
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Family: Pinaceae
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Genus: Pinus
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