This is the largest family among all gymnosperms and the most important economically. It has 10 genera with 250 species, confined mainly to the Northern Hemisphere. Pine trees include the main forest-forming species in temperate and moderately cold regions of Europe, Asia and America. Only one species penetrates into the Southern Hemisphere - the pine of Mercus (Pinus mercusii), which is found on the islands of Sumatra, Borneo, Java. Within the tropics, pine grows only in the mountains in a temperate climate.
Compared with other coniferous families, pine appeared later than all - the genus pine is known from the Jurassic, spruce and cedar from the Lower Cretaceous, fir, larch and other genera from the tertiary sediments of the Cenozoic era. This, apparently, explains the large volume of species within some genera - pine has 100 species, fir and spruce - 40-50 species each. Among them there are many young species that arose in the Cenozoic era, so many pine trees bear the features of xeromorphism.
Pine - mostly evergreen, rarely deciduous plants. Most often, these are trees with a height of 20-30 m, only certain species can reach large sizes, for example, the height of Western larch (Larix decidua) is from 50 to 80 m. Some species have the shape of a shrubbery bush.
Pine trees, as a rule, are long-livers; under favorable conditions, some pine species survive up to 3-4 thousand years, although the average age is 200-400 years. The leaves of most species have the shape of needles, less often they are scaly or linear. All pine trees have wintering buds, often reliably protected by resinous substances. The pine root system is characterized by abundant branching of lateral suction roots, almost all species are mycorrhizal. Wood has well-defined annual rings and a system of horizontal and vertical resin moves.
The large polymorphism of the vegetative organs, sometimes combined with high specialization, enables them to master the most diverse environmental conditions within their range. Along with this, pine trees are characterized by relative uniformity of reproductive organs. All pine are monoecious plants. Male cones - microstrobils - solitary or collected in loose constrobiles (Fig. 86). They consist of an axis on which flat microsporophylls are located with a dense spiral. On their lower side, 2 submerged microsporangia are formed. Dust particles in most of them are equipped with two air sacs, which facilitate their spread over great distances (with the exception of larch, tsuga and pseudo-tsuga). Dust particles have 2 prothallic cells. Female cones - constrobils, as a rule, are single, on the axis are small hiding scales, in the sinuses of which large seed scales - megastrobils sit freely, without growing together with them. On the upper side of the seminal scales are 2 ovules with one free integument. Before pollination, the cone axis lengthens slightly and the seed scales move apart, which contributes to pollination.
Seeds ripen either in the year of formation of the cone (in spruce), or the next year (in pine). The embryo in different species has from 4 to 18 cotyledons. In pine trees there is a huge variety of forms of cones, but at the same time, in all species, seed scales have a leathery or woody consistency. In fir and false larch, cones crumble during ripening, in the remaining genera they fall whole. The sizes of mature cones range from 2-3 cm (in some species of larch) to 30-50 cm (in some species of pine).
The economic importance of pine is extremely great. Many types of wood are highly regarded as building materials in carpentry. Smooth spruce and fir wood, which has the most valuable acoustic properties, is used to make the best musical instruments. Of great importance is pine wood in the pulp and paper industry. However, pine is of no less importance in improving the ecological environment through the release of ozone and bactericidal volatile substances. Therefore, in addition to natural forests in both the Northern and Southern Hemispheres, artificial plantations of mainly pine and spruce are widely cultivated.
The pine family is divided into 3 subfamilies by the presence or absence of shortened shoots: fir subfamily (Abietinae), larch subfamily (Laricoideae) and pine subfamily (Pinoideae).