The Coulter Pine or Big-cone Pine (Pinus coulteri) is a native of the coastal mountains of southern California (United States) and northern Baja California (Mexico). Isolated groves are found as far north as the San Francisco Bay Area in Mt. Diablo State Park and Black Diamond Mines Regional Preserve. This erect, medium-sized pine prefers south-facing slopes between 200-2300 m (600-7500 ft) elevation, and tolerates dry rocky soil. The tree most often appears in mixed forests. The species is named after Thomas Coulter, an Irish botanist and physician.
The size ranges from 10-24 m (30-80 ft) tall, and a trunk diameter up to 1 m (3 ft). The trunk is vertical and branches horizontal to upcurved. The leaves are needle-like, in bundles of three, glaucous gray-green, 15-30 cm (6-12 in) long and stout, 2 mm (0.01 in) thick. The outstanding characteristic of this tree is the large, spiny cones which are 20-40 cm (8-16 in) long, and weigh 2-5 kg (4-10 lbs) when fresh. Coulter Pines produce the largest cones of any pine tree species (people are actually advised to wear hardhats when working in Coulter Pine groves), although the slender cones of the sugar pine are longer. The large size of the cones has earned them the nickname "widowmakers" among locals. The wood is weak and soft, so that the species is little used other than for firewood. It is also occasionally planted as an ornamental tree in parks and large gardens.