Monterey pine, insignis pine (Little 1980), radiata pine.
Syn: Pinus tuberculata D. Don; P. insignis Douglas ex Loudon (Kral 1993, Millar 1986).
It hybridizes naturally with P. attenuata (P. × attenuradiata Stockwell & Righter; note that this name was applied to an experimental hybrid specimen).
One variety, Pinus radiata D. Don var. binata (Engelmann) Lemmon, the Guadalupe Island pine (syn: P. insignis var. binata Engelmann; P. muricata var. cedrosensis Howell; P. radiata var. cedrosensis (Howell) Silba) (Perry 1991).
Trees 15-30(-64) m tall, 30-90(-280) cm in diameter, contorted to straight; crown broadly conic, becoming rounded to flattened, very shallow (10-20% of height) in closed stands. Red-brown, turning gray with age, furrowed between elongate-rectangular scaly ridges. Primary branches variably level, downcurved or ascending, often bearing old cones; twigs slender, red-brown, sometimes glaucous, aging gray, rough. Buds ovoid to ovoid-cylindric, red-brown, ca. 1.5 cm, resinous. Needles 2 (var. binata) or 3 (type variety) per 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)1.5-2 cm, base persistent. Pollen cones ellipsoid-cylindric, 10-15 mm, orange-brown. Seed cones maturing in February, 2 years after pollination, persistent 6-20(-40) years, often serotinous, numerous, solitary to whorled, spreading to recurved, curved, mostly asymmetric (usually symmetric in var. binata and occasionally so in var. radiata), ovoid before opening, broadly ovoid when open, 7-15 cm, yellow-brown, lustrous, scales rigid, stalks to 1cm; apophyses toward outer cone base mostly increasingly mammillate (but not in var. binata), 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. 6 mm, dark brown; wing 20-30 mm. 2n=24 (Little 1980, Kral 1993, M.P. Frankis e-mail 1999.03.05, pers. obs.).
The type variety occurs naturally only at three localities in a fog belt on the coast of central California (at 30-400 m elevation; 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 (at 600-1200 m elevation) HERE is a Google Maps link to it on Isla Guadalupe, where the trees are restricted to steep slopes at the highest elevations at the northern end of the island (Rogers 2002). On Isla Cedros, Rogers (2002) 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 14 km. Their locations on the island may be moisture limited (Libby et al. 1968) because conditions are dry--lower elevations receiving less than 250 mm of precipitation annually. However, fogs and mist are common at higher elevations (Perry 1991) ... No census has been taken on the Monterey pines here--their numbers are far greater than those on Guadalupe Island--and no comprehensive map of their distribution has been made."
Due to its rarity, the species is of conservation concern, with some natural populations receiving protection (Kral 1993, Little 1980, Perry 1991); var. binata is classified Endangered. USDA hardiness zone 8. See also Thompson et al. (1999).
Its cones are serotinous, i.e. they remain closed until opened by the heat of a forest fire; the abundant seeds are then discharged to regenerate the burned forest. The cones may also burst open in hot weather (Little 1980).
Along the California coast it has escaped from cultivation, and from there into southern coastal Oregon it shows signs of naturalizing. It has been introduced as a timber tree in vast areas of New Zealand (where it is the most common tree), Australia, Chile, SW Europe and South Africa (Little 1980, Kral 1993, Lavery & Read in Richardson 1998). Hardy to Zone 8 (cold hardiness limit between -12.1°C and -6.7°C) (Bannister and Neuner 2001).
The three remaining native stands of var. radiata are infected and under threat of extinction from pitch canker, a fungal disease native to the southeast United States and found (in 1986) to have been introduced to California. When trees begin to die of the disease, they attract bark beetles which provide a pathway for infection of other trees. In some stands, 80-90% of trees are infected. If the disease is introduced in agroforestry areas dependent upon radiata pine, such as New Zealand, it could have catastrophic effects in those countries as well (Anonymous 1999).
In its native range, this species is a principal host for the dwarf mistletoe Arceuthobium littorum (Hawksworth and Wiens 1996).
In the United States, a tree measured by Michael Kauffmann (2016) in spring 2016 is 178.7 cm dbh, height 48.77 m, crown spread 26.52 m; it grows in in Rohner Park, Fortuna, CA, and is about 100 years old. Note that this tree is not within the species' native range, though it is in an area where the species is becoming naturalized.
The largest trees are now found in New Zealand, where a specimen 103 cm dbh and 64 m tall can be found in Atiamuri at NZ Forest Products, Ltd., and a tree 245 cm dbh and 49 m tall was recorded at Geraldine, South Canterbury (Burstall and Sale 1984); it was remeasured in 2012 at 47.4 m tall (but this time a laser measurement) and 280.1 cm dbh (New Zealand Notable Trees). The largest specimen reported from South Africa was in a plantation at Tokai Forest, near Cape Town, and was 53.0 m tall when climbed and measured on 2008.01.25 (Leon Visser email 2014.11.05).
It can most easily be seen on the Monterey Peninsula, where it occurs on the hills in the interior of the peninsula. Most peninsular stands have suffered the depredations of axe and bulldozer, and nowadays the species is most comonly visited at Point Lobos State Park (Peattie 1950).
The epithet radiata refers to radial markings visible on the apophyses of some cones (Farjon 2010).
This is the most common pine in the southern hemisphere, where no pines are native (except that Pinus merkusii barely crosses the Line in Sumatra).
Anonymous. 1999. Fungus threatens pines worldwide. American Forests, Autumn 1999, page 14.
Don, D. 1836. Descriptions of five new species of the genus Pinus discovered by Dr. Coulter in California. Trans. Linn. Soc. London 17:439-444.
Libby, W. J., M. H. Bannister and Y. B. Linhart. 1968. The pines of Cedros and Guadalupe Islands. J. Forest. 66:846-852.
Kauffmann, Michael. 2016.06.09. Record Monterey pine (Pinus radiata). blog.conifercountry.com/2016/06/record-pinus-radiata/, accessed 2016.06.10.
Millar, C.I. 1986. The Californian closed-cone pines; a taxonomic history and review. Taxon 35: 657-670.
Rogers, Deborah L. 2002. In situ genetic conservation of Monterey pine (Pinus radiata D. Don):Information and recommendations. Report no. 26. Genetic Resources Conservation Program, Division of Agriculture and Natural Resources, University of California. 92pp.
Rogers, D.L., J.J. Vargas Hernández, A.C. Matheson, and J.J. Guerra Santos. 2002. The Mexican island populations of Pinus radiata: an international expedition and ongoing collaboration for genetic conservation, in Forest Genetic Resources No. 30. www.fao.org/docrep/005/y4341e/Y4341E07.htm, accessed 2011.02.25.
Farjon and Styles (1997) provide a detailed account of var. binata, with illustrations.
Last Modified 2016-06-10