Pinus radiata

D. Don 1836

Common names

Monterey pine, insignis pine (Little 1980), radiata pine.

Taxonomic notes

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 is was applied to an experimental hybrid specimen).

One variety, binata (Engelmann) Lemmon, the Guadalupe Island pine (= P. insignis var. binata Engelmann; P. muricata var. cedrosensis Howell; P. radiata var. cedrosensis (Howell) Silba) (Perry 1991).

Description

Trees 15-30 m tall, 30-90 cm in diameter, contorted to straight; crown broadly conic, becoming rounded to flattened. Bark gray to reddish-brown, 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. 1.5 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, mostly serotinous and persistent 6-20(-40) years, 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).

Range

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. Due to this rarity, the species is of conservation concern, with some natural populations receiving protection (Kral 1993, Little 1980, Perry 1991); var. binata is classified Endangered, with under 100 senescent trees left on Guadalupe and a few thousand on Cedros (Lavery and Read in Richardson 1998). USDA hardiness zone 8. See also Thompson et al. (1999).

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).

Big tree

Diameter 213 cm, height 38 m, crown spread 28 m. Locality: Downing's Forest, CA (American Forests 1996).

Even larger 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). More recently (2009.03), a tree 258.1 cm dbh and 41.9 m tall with a crown spread of 33.8 m was measured at Brooklands Park in New Plymouth (R. Van Pelt email 2009.04.14).

Oldest

Dendrochronology

Ethnobotany

Observations

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).

Remarks

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).

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).

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).

Citations

Anonymous. 1999. Fungus threatens pines worldwide. American Forests, Autumn 1999, page 14.

Millar, C.I. 1986. The Californian closed-cone pines; a taxonomic history and review. Taxon 35: 657-670.

See also

Burns & Honkala (1990).

Farjon and Styles (1997) provide a detailed account of var. binata, with illustrations.

FEIS database.

This page co-edited with M.P. Frankis, 1999.03.