37.
Pinus attenuata
Lemmon, Mining Sci. Press. 64: 45. 1892.
Knobcone pine
Pinus tuberculata
Gordon 1849, not D.Don 1836
Shrubs or trees to 24m; trunk to 0.8m diam., usually straight; crown mostly narrowly to broadly conic. Bark purple-brown to dark brown, shallowly and narrowly fissured, with irregular, flat, loose-scaly plates, on upper sections of trunk nearly smooth. Branches ascending; twigs slender, red-brown. Buds ovoid to ovoid-cylindric, dark red-brown, aging darker, ca. 1.5cm, resinous; scale margins fringed, apex attenuate. Leaves 3 per fascicle, spreading or ascending, persisting 4--5 years, (8--)9--15(--20)cm ´ (1--)1.3--1.8mm, straight or slightly curved, twisted, yellow-green, all surfaces with fine stomatal lines, margins serrulate, apex abruptly conic-subulate; sheath (1--)1.5--2cm, base persistent. Pollen cones ellipsoid-cylindric, 10--15mm, orange-brown. Seed cones maturing in 2 years, serotinous, long-persistent, remaining closed for 20 years or more, or opening on burning, in whorls, hard and heavy, very asymmetric, lanceoloid before opening, ovoid-cylindric when open, 8--15cm, yellow- or pale red-brown, stalks to 1cm; apophyses toward outside base increasingly elongate, mammillate or raised-angled-conic, downcurved near base, scarcely raised on branchlet side, rhombic; umbo central, low-pyramidal, sharp, upcurved. Seeds compressed-oblique-obovoid; body ca. 6--7mm, nearly black; wing narrow, to 20mm. 2 n =24.
Fire successional on dry slopes and foothills of Sierra Nevada and the Cascade and Coast ranges; 300--1200m; Calif., Oreg.; Mexico in Baja California.
Pinus attenuata , mostly a chaparral species, bears cones at an early age. Its seed crops are heavy, and a hot fire permits the seeds to be released. It forms hybrids with P . muricata and P . radiata .
