Description: Large to very large tree with broad, open, conical crown of spreading branches; three distinct geographic varieties.

Height: 20-40 m, exceptionally to 72m in Siskiyou mtns.

Diameter: 0.8-1.2 m, sometimes larger.

Needles: evergreen; usually two or three in bundle (two to five in varieties); generally 10-20 cm long; stout, stiff, dark green. Smell of turpentine when crushed.

Bark: blackish, rough and furrowed into ridges; on trunks of small trees (Blackjacks), becoming yellow-brown and irregularly furrowed into large, flat, scaly plates; on mature trees, may be up to 10cm thick.

Flowers: Males deep rich purple, ovoid, 2 cm, lengthen and curve to 4 cm, cylindric, when shedding pollen in June. Females 1-5 terminal, ovoid, dull red, soon deep purple conelets, 2 cm; deflexed scales.

Cones: 5-15 cm long, conical or egg-shaped, almost stalkless, light reddish-brown; opening and shedding at maturity (2nd year), leaving a few cone-scales on twig; cone-scales raised and keeled, ending in short, sharp prickle; small (4-9 mm) brown to yellow seeds, often motteld darker, with long-wings (15-25 mm). Borne after ~16 years.

Habitat: Mostly in mountains in pure stands, forming extensive forests; also in mixed coniferous forests. Grows on a variety of soils, but best on well-drained deep sandy gravels. Usually occurs at lower elevations than Jeffrey Pine, with which it pretty much defines the California plant community Yellow Pine Forest (m14). In the Pacific Northwest, Ponderosa Pine occurs in both Douglas-Fir Forest and Oak-Pine Forest.

Range: S British Columbia east to SW North Dakota, south to Trans-Pecos Texas, and west to S California; also N Mexico; from sea-level in north to 2700 m in south; the best developed stands at 1200-2400 m.

This is the most widely distributed and common pine in North America. The typical variety, Ponderosa Pine or Pacific P.P. (var. ponderosa), has long needles, three in a bundle, and large cones; occurs in the Pacific coast region. Rocky Mountain P.P. or Interior P.P. (var. scopulorum Engelm.) with short needles, two in a bundle, and small cones, is found in the Rocky Mountain region (forest types Black Hills Forest and Rocky Mountain Ponderosa Pine Forest). Arizona Pine or Arizona P.P. (var. arizonica (Engelm.) Shaw), occurring mainly in SE Arizona (South West Montane Forest), has five slender needles in a bundle. Lewis & Clarke first saw this pine, but first described when David Douglas, the Scottish botanical explorer, found it in 1826 and named it for its ponderous, or heavy wood. Introduced to UK the year after - biggest specimens are c 40m after 150 years - some of the original plantings still surviving. Trees typically live to 300 years and may live up to 500 (record 726). Seedlings have vigorous tap roots to 55 cm in one year. Quail, Nutcrackers, Squirrels and many other kinds of wildlife consume the seeds; and chipmunks store them in their caches, thus aiding dispersal.

Information: Audubon (1980), Lawrence (1985), Mitchell (1988), Leathart (1991), FNA 2 (1993), Bean III (1976)

Sources: Weasdale Nurseries, Newbiggin-on-Lune, Cumbria;
Chiltern Seeds, Milnthorpe, Cumbria

Purchased: Spring 1993 and again in 1994.

Planted: 1993.04.03 and 1993.04.17, and again in 1994. Seeds in spring 1995.

Progress: none of the trees from Weasdale have survived, almost the only trees from this source with which we have had any problem. The most likely cause seems to be a failure to establish new mycorrhizal fungal associations after the root tip damage caused by transplantation. This would perhaps be less of a problem if we were planting into an area which had been growing conifers previously. The trees we have grown from seed (11 of 14 germinated) seem to have established OK, though these seem to suffer losses if repotting is too disruptive. The best technique seems to be to sow only one seed per pot (or to thin germinations to only one plant per pot), and keep potting the trees on with minimal root disturbance. By the nature of the roots, very deep pots are needed - we use cut off 2 litre PET bottles for the earliest stages, then extra-deep 4 litre pots, planting out before anything bigger is needed. The first ones planted out went out in late autumn 1996, but one of these lost its tree shelter and was then mown over - one hazard of using trees this small :-( The survivor was at 0.3m in late 1998, with a healthy top bud promising strong growth in the 1999 season. Two more seedlings went out in mid-May and early June 1999 and all grew away pretty well. There is some needle browning in autumn 2002, but this is probably to be expected - needles are shed after a few years. By 2004.09.27, two of the trees were well-established at 2.6m, and the furthest south (perhaps more shaded) was 2.1m. All continue to show some browning of the needle tips, though I think this year's needles are OK (we have had a wet summer this year).

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