Pinus radiataMonterey Pine
Pinus radiata by Joanne Taylor
California is home to a variety of conifers. Out of the 74 conifers found in the western United States, 57 grow in California and 27 are endemic, including the Monterey pine. It is one of three signature trees planted by William Hammond Hall in 1872 to create the original tree canopy in Golden Gate Park. Found naturally in three distinct coastal areas of California, Pinus radiata (Monterey pine) is considered a "closed-cone pine," with cones that remain unopened on its branches for years. The cones are serotinous, needing fire to stimulate opening of the cone scales and release of the seeds for dispersal. Occasionally the heat of a very warm day will be enough to open the cones. It is closely related to Pinus attenuata (knobcone pine) and Pinus muricata (bishop pine), the other two closed-cone pines, or as they are sometimes called, "fire pines."
The needles come in bundles of three, are dark green and flexible, and have a blunt tip. The height of the tree varies from 40 to 100 feet with a girth varying from three to six feet. The cones are small – three to five inches – and asymmetrical, clinging to the branches at an oblique angle.
In recent years, populations of Monterey pine have declined due to the fungus Fusarium circinatum, which causes pitch canker disease. The disease has spread to many species of California Native pines, however, the Monterey pine has been the most severely affected.
Selective breeding and additions of growth hormones by timber companies have produced a new hybrid with far better quality timber than is present in the original species. Its fast-growing nature combined with these new qualities have made it the most planted pine in the world, with vast plantations in Australia, South Africa, Argentina, New Zealand, Kenya and Chile. The new hybrid has been so successful abroad that it is now considered an invasive species in some countries, often crowding out native flora, and thus diminishing the associated wildlife.
||Well drained sites, close to the ocean to emulate their native habitat and prevent stress.
||Pollen cones 10-15 mm orange brown; Seed cones maturing in Februrary two years after pollination 7-15cm, yellow-brown
||Large canopy tree requiring a lot of space.
||The three areas where it naturally occurs are all in the fog belt in central California: Ano Nuevo, Monterey Peninsula and Cambria.
In its native range, it is the principal host for the dwarf mistletoe Arceuthobium.
The stand of Monterey Pines growing in the town of Pacific Grove serve as winter habitat for monarch butterflies.
More about pitch canker disease
Pinus radiata is located in the South Africa Garden (Bed 32A), the Temperate Asia Garden (Bed 19B) and the Mesoamerican Cloud Forest (Bed 26D.)
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IN BLOOM CONTRIBUTORS:
Photos by Docent Joanne Taylor; text by Docent Kathy McNeil; profile by Associate Curator David Kruse-Pickler