Pinus (redirected from Pinus cubensis, Pinus ponderosa, Pinus radiata)

Pinus 

(pine), a genus of coniferous evergreen trees and, less commonly, spreading shrubs of the family Pinaceae. The plants range in height from 1.5 to 50 m, sometimes reaching 75 m. In young trees the crowns are conical and have horizontal branches in whorls; older trees have rounded or umbellate crowns. The bark is scaly. The sharp, green or grayish blue needles are trihedral or rounded on the back and have rough margins; they are 2–20 cm long and 1–2 mm thick. Fascicles of two, three, or five leaves are borne at the tips of short shoots; they remain on the tree for two or more years. The numerous microstrobiles are compact and yellow or reddish in color. The cones are usually 3–10 cm long (in the North American sugar pine [P. lambertiana], up to 50 cm) and 2.5–8 cm in diameter; they are pendant and indéhiscent. The scales are thickened at the apex. The seeds are nutlike and usually winged. The root system is extensive, with a deep vertical taproot and widely spreading lateral roots.

Pines are photophilic. They form forests and groves on well-drained soils and rocky slopes; they can also tolerate a marshy environment. The plants may live as long as 300 to 350 years. There are about 100 species, distributed in the forest zone of Eurasia and North America and, less frequently, in tropical mountains of the northern hemisphere. The USSR has about 12 species.

The Scotch pine (P. silvestris), a tree measuring 20–40 m in height, forms forests in the European USSR and Siberia. The leaves are in fascicles of two, and the elongate-oval cones are 3–7 cm long. The Scotch pine furnishes lumber, fuel, pitch, resin, tar, oleoresin turpentine, volatile turpentine oil, and rosin. Vitamin C is obtained from the needles, and the sawdust is used for growing fodder yeasts. Scotch pines help to reinforce sands.

The closely related species P. lapponica grows on the Kola and Scandinavian peninsulas; the species P. pallasiana grows in the mountainous regions of the Crimea and Western Transcaucasia. P. pityusa, which is noted for its shiny reddish brown cones, is found in Western Transcaucasia. In the USSR pine species having needles in fascicles of five include the Siberian stone pine (P. sibirica), dwarf stone pine (P. pumila), and Korean pine (P. koraiensis). The Korean pine reaches a height of 40 m. Its needles are 8–12 cm long, and its edible seeds are 1.4–1.7 cm long. The tree grows in the Far East, in the mountains of Manchuria and northeastern Korea and in Japan (Honshu Island).

REFERENCES

Derev’ia ikustarniki SSSR, vol.. 1. Moscow-Leningrad, 1949.
Dallimore, W., and A. B. Jackson. A Handbook of Coniferae and Ginkgoaceae, 4th ed. London, 1966.
Mirov, N. T. The Genus Pinus. New York [1967].

T. G. LEONOVA