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Pinus radiata D.Don 1836
pronounced: PY-nuss ray-dee-AH-tuh
(Pinaceae – the pine family)
common names: Monterey Pine, Radiata Pine
Pinus is Latin for a pine tree; radiata is from the Latin radiatus, furnished with rays. If any reader is worried about the clash of the –us of Pinus and the –a of radiata, note that, despite its ending, pinus is a feminine noun, and requires a feminine adjective.
Pinus radiata is a native of Monterey County, California. It can grow up to 30 m tall in its natural state, but up to 50 m in high quality plantation areas. The form of the tree in closely-spaced plantations is narrow, while open-growth trees become spreading. Its bark is dark brown with deep ridges. The leaves are dark green, rigid, with a pointed tip and finely toothed margin, 7.5–15 cm long. The leaves are grouped into threes with a 1–1.5 mm long basal sheath enclosing them. Leaves are shed with the sheath intact after 3 or 4 years.
The tree produces both male and female cones. The numerous male cones, clustered at the tips of the branches, are cylindrical, 1–1.5 cm long. The female cones are obliquely egg-shaped with the outer side larger than the inner, 7–15 by 6–8 cm when closed. The scales are glossy, and greyish brown. The seeds are blackish, ellipsoid, 6 mm long with a wing 2.5 cm long. Viable seed may remain in the cones for several years. The cones 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 very hot weather.
This is the most common pine tree in the southern hemisphere, where no members of this genus are native, except for Pinus merkusii that creeps marginally south of the equator in Sumatra. In the rush to reduce Australia’s dependence on imports of softwood, many thousands of hectares of native bushland were cleared and planted with this pine. The extent of the plantation was often determined by adjacent land ownership and steepness of terrain, which means that plantations often have a common border with conservation reserves and other native bushland. By 2003 there were over 716,500 ha of Radiata pine in Australia. The species has weed potential both in Australia and overseas. Research to date has demonstrated its invasive potential and its ability to alter structure and species composition of native vegetation. This leads to an impoverished plant community and reduced habitat value for native fauna, which is particularly important where native vegetation is already greatly reduced in extent. The threat becomes so much greater when these remnants lie next to pine plantations that are much larger in extent than the native vegetation. Pines have winged seeds which are carried on the wind to neighbouring bushland, whether it be heathland and heathy woodland, lowland grassland and grassy woodland, dry sclerophyll forest and woodland, damp sclerophyll forest, or riparian vegetation.
The heartwood is reddish brown varying to shades of yellow; the sapwood is usually pale yellow to white. The grain is generally straight. An often pronounced difference in colour between earlywood and latewood results in a very distinctive figure when the timber is sawn tangentially. Knots are usually present. This is a softwood, and easy to work with hand tools. It machines and turns well, but cutting blades need to be kept very sharp to avoid surface ridging. When the timber is being nailed, nails will sometimes follow the growth rings; but nailing guns give good results.
Preservative impregnated poles are used for pole frame construction and transmission poles. This is a commonly used general softwood used as dressed, seasoned timber in house construction, joinery and fencing. It is also used in structural plywood, scaffold planks, paper making, and particleboard.
A number of Lepidoptera species use this as a food plant, including:
• the Twig Looper Ectropis excursaria;
• the Black and White Tiger Moth Spilosoma glatignyi;
• the moth Arachnographa micrastrella;
• the Lucerne Looper Zermizinga sinuata;
• the Wattle Snout Moth Pararguda nasuta;
• the Omnivorous Tussock Moth Acyphas semiochrea;
• the moth Chlenias auctaria;
• the moth Chlenias banksiaria; and
• the moth Orgyia australis.
Photographs taken 2011, Horseshoe Bay
Page last updated 8th February 2018