subgenusPinus, sectionTrifoliae (Duhamel), subsectionAttenuatae (Van Der Burgh).
Pinus radiata, as described in 1836 by David Don (1799–1841), in Transactions of the Linnean Society of London, vol. 17:442, is commonly known as Monterey pine, insignis pine, or radiata pine. The species name reflects how the mature seed cones form rings, radiating around the branches.
Ethnobotany. As timber, P. radiata is suitable for a wide variety of uses, and has a resinous fragrance while being worked. It holds screws and nails well and takes paint and stain without difficulty, and modern kiln dried timber is very easy to work. It is about 1/3 heavier than dried western red cedar. It is brittle when bent, so does not have the same load-bearing features as Douglas-fir, Pseudotsuga.
P. radiata is used in house construction as weatherboards, posts, beams or plywood, in fencing, retaining walls, for concrete formers. It is also used to a limited extent in boat building where untreated ply is sometimes used, but must be encased in epoxy resin to exclude moisture.
Description. Monterey pine is an evergreen, coniferous species of tree that grows to mature heights of 50 to 100 feet (15 - 30 m), with a contorted to straight trunk 12 to 36 inches (30 - 90 cm) in diameter, measuring at breast height; and a broadly conic crown, becoming rounded to flattened with age. Crown density is very shallow (10 to 20% of height) in closed stands.
Bark is red-brown in color, turning gray with age, furrowed between elongate-rectangular scaly ridges.
Primary branches are variably level, downcurved or ascending, often bearing old cones.
Twigs are slender, red-brown in color, sometimes glaucous, aging gray, rough.
Foliar buds are ovoid to ovoid-cylindrically shaped, resinous, red-brown in color, and circa 0.6 inch (1.5 cm) long.
Leaves (needles) are borne in fascicles of 2 in var. binata or 3 in the type variety. They are spreading-ascending in orientation, persisting 3 to 4 years on the tree. Individual needles measure 3.6 to 6 inches (9 - 15 cm) long by 0.026 to 0.072 inch (1.3-1.8 mm) thick, and are straight or slightly twisted, and deep yellow-green in color. All surfaces bear fine stomatal lines, with serrulate margins, and conic-subulate apices.
Foliage sheaths measure 0.6 to 0.8 inch (1.5 - 2 cm) long with a persistent base.
Pollen cones are ellipsoid-cylindrically shaped, measuring 0.4 to 0.6 inch (10 - 15 mm) and orange-brown in color.
Seed cones mature in February, 2 years after pollination, and are persistent for 6 to 20 (exceptionally to 40) years on the tree. They are often serotinous, numerous, solitary to whorled, spreading to recurved, curved, mostly asymmetric (usually symmetric in var. binata and occasionally so in var. radiata), ovoid shaped before opening, broadly ovoid when open, measuring 2.8 to 6 inches (7 - 15 cm) long, colored lustrous yellow-brown.
Seed scales are rigid with stalks up to 0.4 inch (1 cm) long Apophyses toward outer cone base are mostly mammillated (but not in var. binata), those on inner cone side and middle and apex of cone are more level. Umbos are centrally oriented, mostly depressed, with a small central boss or occasionally with a slender, deciduous prickle.
Seeds are compressed-ellipsoid shaped with a circa 0.24 inch (6 mm body) and a dark brown, 0.8 to 1.2 inch (20-30 mm) wing.
Distribution. This species is native to USA — three localities in a fog belt on the coast of central California at elevations of 100 to 1,250 feet (30 - 400 m) above sea level. The localities include one in San Mateo and Santa Cruz counties, one in Monterey County, and one in San Luis Obispo County) while variety binata is found on Islas Guadalupe and Cedros, off the west coast of Baja California Norte, Mexico, growing at 2,000 to 5,000 feet (600-1200 m) of elevation), where the trees are restricted to steep slopes at the highest elevations at the northern end of the island. On Isla Cedros, Deborah Rogers reports that "the pines occur in two main populations: inland towards the center of the island and at the northern end of the island, separated by approximately 8 miles (14 km)." Their locations on the island may be moisture limited because conditions are dry—lower elevations receiving less than 10 inches (250 mm) of precipitation annually. However, fogs and mist are common at higher elevations.
It has been introduced as a timber tree in vast areas of New Zealand (where it is the most common tree), Australia, Chile, southwestern Europe and South Africa. It has become naturalized at considered invasive in many of these places.
Hardy to USDA Zone 8 — cold hardiness limit between 10° and 20°F (-12.1° and -6.7°C).