PINUS 



PINUS 



2633 



staminate ones axillary, clustered at the base of the 

 young shoots, catkin-like, yellow, orange, or scarlet, 

 composed of spirally arranged numerous 2^celled anthers 

 with the connective enlarged and scale-like at the apex 

 (Fig. 2956) ; pistillate lateral or subterminal, greenish or 

 purplish, consisting of numerous spirally arranged 

 scales each in the axil of a small bract and bearing 2 

 ovules inside near the base (Fig. 2957) : cone subglobose 

 to cylindric, with woody scales closely appressed before 

 maturity and tightly inclosing the seeds, which are 

 usually furnished with a long thin wing, but in some 

 species are wingless or short- winged; the apex of the 

 scales is usually more or less thickened and the exposed 

 part, which is usually rhombic in outline and termed 

 apophysis, is often protracted into prominent bosses or 

 knobs; the apophysis is terminated by the umbo, 

 usually differing in color and ending mostly in a spine 

 or prickle. In P. Strobus and the allied species the 

 apophysis is flat and thin, and bears the spineless umbo 

 at the upper end, while in most other pines the apophysis 

 is thickened and transversally keeled and bears the 

 umbo in the middle. These differences belong to the 

 most important characters in the grouping of the spe- 

 cies: other valu- 

 able characters are 

 furnished by the 

 structure of the 

 Ivs., which contain 

 either 1 or 2 fibro- 

 vascular bundles 

 and usually 2 or 

 more resin -ducts, 

 being either ex- 

 ternal (or periph- 

 eral), i.e., situated 

 beneath the epider- 

 mis; or medial (or 

 parenchy matous) , 

 i.e., inclosed by the 

 tissue of the If.; or 

 internal, i.e., close 

 to the fibre-vascu- 

 lar bundles; some 



species, as P. Armandi, P. resinosa, P. sinensis, also P. 

 txcdsa, P. Lambertiana, P. virginiana, and the like, have 

 resin-ducts hi 2 positions, either external and medial 

 or internal and medial, but such combinations are not 

 found in all the Ivs. of these species. Strengthening 

 cells, i.e., cells with thickened walls, are mostly present 

 beneath the epidermis and often surround the resin- 

 ducts, sometimes also along the fibro-vascular bundles. 

 (See Figs. 2958-2961.) The number of the fibro-vascu- 

 lar bundles and the position of the resin-ducts can be 

 readily seen with a common magnifying glass in thin 

 cross-sections made with a sharp razor from the middle 

 of the If. and placed on a glass plate. About 80 species 

 are known, distributed throughout the northern hemi- 

 sphere from the arctic circle to Mex. and the W. Indies, 

 X. Afr., and the Malayan Archipelago; in the tropical 

 and subtropical regions they are confined to the moun- 

 tains. In the following enumeration the species are 

 grouped according to Shaw's classification. To facilitate 

 the determination of the cult, species, a key is given to 

 determine plants without cones, but owing to the great 

 variability in pines this key may fail, if the plant in 

 hand represents some uncommon variation. Good 

 illustrations are found in Sargent, Silva of N. America, 

 vol. 11; Lambert, Description of the Genus Pinus; 

 Lawson, Pinetum Britannicum; Forbes, Pinetum 

 Woburnense; Antoine, Die Coniferen; Clinton-Baker, 

 Illustrations of Conifers, vol. I; Pard6, Iconographie des 

 Coniferes (in course of publication). For the horti- 

 cultural varieties, see Beissner, Nadelholzkunde, second 

 edition (1909), and the new edition by A. H. Kent of 

 > eitch's Manual of the Coniferae. Among other impor- 

 tant works may be mentioned E. A. Carriere's TraitS 



general des Coniferes, second edition, 1867; Heinrich 

 Mayr's Die Waldungen von Nordamerika, 1890; 

 G. Engelmann's Revision of the Genus Pinus, in Trans- 

 actions of the Academy of Science of St. Louis, pub- 

 lished in 1880; Maxwell T. Masters in Journal of the 



2958. Pinus Strobus. 

 Leaf with a single fibro-vascular bundle 

 (a) , usually two external resin-ducts (6) ; 

 strengthening cells (c) only beneath the 

 epidermis; stomata (d) only on the two 

 inner sides. 



-C 



-a 



2959. Pinus Coulteri. 



Leaf with two fibro-vascular bundles (a) ; several medial resin- 

 ducts (b) ; strengthening cells (c) around the resin-ducts, several 

 layers beneath the epidermis and along the inner and outer side of 

 the fibro-vascular bundles; stomata (d) all around. 



Linnean Society, vols. 22 (1886) and 27 (1889); Conifer 

 Conference in Journal Royal Horticultural Society, 

 vol. 14 (1892); Silva Tarouca's Unsere Freiland-Nadel- 

 holzer (1913); G.R. Shaw's The Pines of Mexico (1909) 

 and The Genus Pinus (1914), both well illustrated. 



The pines are usually tall trees, rarely shrubby, with 

 spreading branches forming a pyramidal or round- 

 topped, in old age often very picturesque head, and 

 clothed with acicular leaves in clusters of 2-5, rarely 

 solitary. The flowers are catkin-like, appearing in 

 spring, the staminate yellow or purple, often conspicuous 

 by their abundance, and the pistillate greenish or pur- 

 plish, developing into subglobose to cylindric, usually 

 brown cones, which sometimes attain 18 or more 

 inches in length, ripening mostly not before the second 

 or rarely the third year. The pines are among the 

 most important timber trees of the northern hemi- 

 sphere, and many of them are valuable for the decora- 

 tion of parks and gardens. 



Young pines are with few exceptions of more or less 

 regular, pyramidal habit; but in old age they are often 

 very picturesque, especially P. Strobus, P. radiata, P. 

 rigida, P. Pinea, P. Cembra, P. nigra, P. parviflora, and 

 others. Of very graceful habit, with slender branches 

 and more or less drooping foliage, are P. excelsa, and 

 the tender P. Ayacahuite, P. longifolia, and P. canari- 

 ensis. The very large cones of some species, as P. Lam- 

 bertiana, P. Ayacahuite, P. Sabiniana, and P. Coulteri, 

 are a conspicuous ornament. Most species are of vigor- 

 ous growth when young, but the foreign species usually 

 grow rather slowly and are therefore well suited for 

 smaller gardens, especially P. koraiensis, P. Peuce, 

 P. Bungeana, P. parviflora; the American P. aristata 

 and P. flexilis may also be recommended for this 



, c 



2960. Pinus palustris. 



Leaf with two fibro-vascular bundles (a) ; several internal resin- 

 ducts (6) , one layer of strengthening cells (c) beneath the epider- 

 mis and on the inner side of the fibro-vascular bundles; stomata 

 (d) all around. 



