The Pines. 317 



the cones, and usually ripen in the autumn of the next year after 

 they blossom. Occasionally the cones remain closed for several 

 yrar<, and in these cases the seeds retain their vitality a long time. 

 The leaves come out from a sheath, iu groups of two, three or five, 

 except iu one species, where they are single. They are linear, and 

 from one to sixteen inches in length, and remain on two or three 

 years, ( r even longer. In transverse section, they show resin-ducts 

 and air-cells that are symmetrical, and, in a given species, very con- 

 s-taut in their arrangement. The seeds of the pines are generally 

 winged, and in some species they are large and edible. The num- 

 ber of cotyledons varies from 4 or 5 to 15 or 18, and is nearly con- 

 stant in a given species. 



1207. In s'une species, as in the sugar-pine, and the heavy yellow 

 pine of the Pacific States, they grow to a size surpassed only by the 

 Seqwrieu, and sometimes they live to a great age. A section of 

 white pine, from Canada, was shown at the Centennial Exhibition 

 at Philadelphia, that was 004 years old, and a plank, without waney 

 edges, was eight feet four inches wide, and nine inches thick. The 

 growth of the pines is most rapid in early years, the annual rings 

 being generally narrower as the trees approach maturity. 



1298. The sap-wood does not change to heart- wood until after 

 many years in some cases 100 or over, and on an average about 

 20 years. This sap-wood is white, but is generally perishable, 

 especially' when exposed to the weather. It is owing to this quality, 

 that second-growth pines have a poor reputation for lumber, and 

 are actually worth but little, except for the coarser uses. 



1299. Commercially, the pines afford the most important timber 

 of the American markets, and immense quantities are used every 

 year in building, fencing, and for exportation. Our space will not 

 admit of a detailed description of all the species found native in the 

 country, which could not be done without involving technical de- 

 scriptions that properly belong to special botanical works. 1 



1300. The pines are divided into two sections, viz.: Strobus and 

 Pinadcr. In the first of these, or the " white pines," the scales of 

 the cones are thin and smooth, and the leaves occur in fives. The 



1 One of the latest revisions of the Pines is given by Dr. George Engel- 

 mann, in the Transactions of the Academy of Science of St. Louis, Vol IV., 

 No. 1. (1880). 



