Trees to 30m; trunk to 0.9m diam., contorted to straight; crown broadly conic, becoming rounded to flattened. Bark gray, deeply V-furrowed, furrow bases red, ridges irregularly elongate-rectangular, their flattened surfaces scaly. Branches level to downcurved or ascending, poorly self-pruning; twigs slender, red-brown, sometimes glaucous, aging gray, rough. Buds ovoid to ovoid-cylindric, red-brown, ca. 1.5cm, resinous. Leaves (2--)3 in a fascicle, spreading-ascending, persisting 3--4 years, (8--)9--15(--20)cm ´ 1.3--1.8(--2)mm, straight, slightly twisted, deep yellow-green, all surfaces with fine stomatal lines, margins serrulate, apex conic-subulate; sheath (1--)1.5--2cm, base persistent. Pollen cones ellipsoid-cylindric, 10--15mm, orange-brown. Seed cones maturing in 2 years, shedding seeds soon thereafter, but often serotinous and persistent 6--20 years, solitary to whorled, spreading to recurved, curved, very asymmetric, ovoid before opening, broadly ovoid when open, 7--14cm, pale red-brown and lustrous, scales rigid, stalks to 1cm; apophyses toward outer cone base increasingly mammillate, those on inward cone side and middle and apex of cone more level; umbo central, mostly depressed, with small central boss or occasionally with slender, deciduous prickle. Seeds compressed-ellipsoid; body ca. 6mm, dark brown; wing 20--30mm. 2 n =24.
General: Pine family (Pinaceae). Monterey pines are native to California and Baja California where they occur in only a few small populations. Mature Monterey pines can reach 38 m in height with trunks up to 2 m in diameter. The young trees begin as compact pyramids but age into varied shapes. The adult canopy is usually rounded to flat-topped. Along the Pacific coast, the winds sculpt Monterey pine canopies into picturesque shapes. The bark is red-brown to blackish brown and has deep furrows. The leaves are glossy, dark green needles, 6-15 cm long that grow in bundles of three. Needles on older trees are sometimes a bluish green. Flowers appear in late winter or early spring. The trees are monoecious; having both male and female flowers (McDonald & Laacke 1990). The yellow male catkins are 12mm long and are generally found on the lateral branches. Female flowers grow throughout the entire canopy. The grayish brown cones are asymmetrically oval, 6 to 15 cm long, and are born on short stalks in clusters of 3 to 7 cones. The scales are smooth and rounded. Each cone contains from 120 to 200 dark brown to black, bumpy winged seeds that are 6-7mm long. The cones remain closed on the tree until the second year or sometimes longer. Cones generally ripen and open from late winter to early spring of the second year. Thereafter, they may remain on the tree where they can open and close several times depending on temperature and moisture. The close-grained wood is light and soft. Although it is not considered an important lumber tree in California, it has been widely planted in areas with Mediterranean climates throughout the world for use as lumber and pulp.
Distribution: Monterey pines are native to California and Baja California. Native Monterey pine forests occupy a small portion of their historical range and are currently restricted to five coastal locations: Año Nuevo in the north, the Monterey Peninsula, Cambria, and on Guadalupe and Cedros islands off the coast of Baja, California in the south.
For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site.
Habitat: Monterey pines grow below 1200 meters in closed cone pine forests and oak woodlands. The species is one of the 18 California species of pines and cypresses that bear closed cones (Dallman 1998:27). The remaining stands of Monterey pine are threatened by numerous factors including urbanization, recreational development, and fire suppression, pests and diseases. Fire suppression has resulted in very old stands of forest, which are more susceptible to attacks from pests and diseases. In the Monterey area, the trees are seriously threatened by an epidemic of “pine pitch canker”, a fungal disease caused by Fusarium subglutans pini. This fungus was recently introduced to California from the southeastern United States and is carried from tree to tree by several native insects including the Monterey pine cone beetle (Conophthorus radiatae), twig beetles (Pitophthorus spp.) and engraver beetles (Ips spp.). Indigenous stands of Monterey pine are also threatened by genetic contamination, which results from crossbreeding with planted trees that were brought in from other areas.
Pinus radiata has an extremely narrow natural range: three coastal areas in California (one in San Mateo and Santa Cruz counties, one in Monterey County, and one in San Luis Obispo County) and off the coast of Baja California, Mexico (Guadalupe Island and debatably also on Cedros Island). Some natural populations of the species are under protection. Along the California coast it has escaped from cultivation, and from there into southern coastal Oregon it shows signs of naturalizing.
Pinus radiata is a much better-formed tree and of greater silvicultural value within its introduced range (Africa, Australia, Europe, and New Zealand, where it is a principal timber tree) than in its native range. It hybridizes naturally with P . attenuata ( P . ´ attenuiradiata Stockwell & Righter).
Although Monterey pines are threatened in their present native habitat, they have been considered a weedy pest in some areas of California where they have escaped cultivation. Millar (1998) uses fossil evidence to support an alternate view: that Monterey pine populations have historically shifted in size and location along the California and Baja coasts in response to changing climate. She suggests, that in order to allow for the continued survival of Monterey pines, establishment of new stands of native stock within the pine’s historical range should be considered as opportunities for their conservation and not as a threat to other native species.
Monterey pines are adapted to soils of medium to heavy texture. Monterey pines have serotinous cones that do not release the seeds unless subjected to high temperatures. Superheating may occur on very hot days or during fire events. Because hot days do not often occur in the Central Coast of California, replenishment of the seed bank is highly dependant on fire (Hillyard 1997).
Monterey pines are ornamental as well as useful. This species is the most widely cultivated pine in the world (Templeton et al. 1997). Monterey pines are also the most widely planted trees for choose-and-cut Christmas tree farms in California. They are excellent shade trees, act as effective wind and sound barriers, and have been used for erosion control.
Be careful to select a proper place to plant these fast growing trees. Monterey pines are the most rapid growing pine of over 90 species that occur in the world (Labadie 1978). Young trees can grow up to 2 meters per year, generally reaching from 12 to 18 meters within 25 years. The trees have an average life span of 80 to 90 years.
These trees require deep, well drained, medium to course textured soils of medium fertility. Trees that are planted on shallow or waterlogged soils may be unstable because of shallow vertical roots. Monterey pines can be damaged or killed in areas where temperatures reach below freezing.
Monterey pines are usually transplanted from containers or bare rootstock grown by commercial nurseries. However, these plants usually come from New Zealand stock. Even though the New Zealand stock originated from California populations, crossbreeding with native populations is considered a threat to the native population’s conservation because of genetic contamination (Cope 1993).
Seed may propagate Monterey pine trees. Handpick mature cones from the trees or from the ground. Air-dry opened cones by spreading them in a sunny, dry place. To open closed cones, drop them into boiling water for 1 to 2 minutes or more, if needed. Remove the seeds from the cones by shaking them out. Although the cones require heat in order to release the seeds, the seeds do not generally require pretreatment in order to germinate. One to three weeks of cold-moist stratification may improve germination, especially for seeds that have been stored (Emery 1988). Monterey pines are not generally propagated by cuttings as, even with bottom heat, the cuttings may take four or more months to form roots.