Limber pines (Pinus flexilis) are timberline trees growing in desert ranges and mountain slopes at elevations as low as 4,000 feet in northern habitats, however, in more southerly climes they only occur much higher. This short, compact pine can be found from Southeast Alberta through the Rockies into western Texas and northern Mexico and west to Idaho, Utah, Nevada and southern California. They require full sunlight.
At the high, frigid, often inaccessible areas where limber pines grow, the snow can fall deep and winds howl throughout the year. This causes the growth form to often be eccentric and contorted. In more sheltered areas, limber pine branches can be unusually long and persistent, extending down to the ground. The branches can bend in the wind without snapping.
Limber pine bark is thick, dark brown or blackish and deeply furrowed. The areas between furrows are broken cross-wise into plates. Where the outer bark is worn away, the dull reddish inner bark is exposed. The bark on branches is smooth and whitish grey or silvery. Twigs are so flexible that they can be twisted around a finger or carefully tied into a knot without breaking.
The yellow-green needles grow in bundles of five and are often curved upward and are forward pointing. The foliage is densely set at the ends of branches and appears tufted.
The short-stalked limber pine cones mature in late summer or early autumn of the second year. The deep reddish-brown seeds are shed in late September or early October. By early winter the cones fall off the trees. The unarmed cone scales are thickened and yellowish brown at the tips and the inner portions are pale reddish brown. The seeds are a critical food for several species, especially Clark’s nutcrackers.
The wood is dense, but soft and knotty. The pale yellow heartwood becomes reddish upon long exposure to air. Although little use is made of limber pine today, early settlers used limber pine wood in place of the white pine with which they were familiar and called it Rocky Mountain white pine. Limbertwig is another common name for P flexilis.
These limber pine specimens were growing along the Bristlecone Trail in Great Basin National Park (Nevada) at about 10,000 feet.