THE PINE FAMILY 



PINACE^ LiNDLEY 



HIS family consists of about 25 genera with some 250 species of trees 

 and shrubs widely distributed in temperate regions throughout the 

 world; they are of especial economic value on account of their soft 

 wood and furnish some of the most extensively used lumber. This 

 is largely due to the structure of the wood, which differs markedly from that of 

 the deciduous- leaved trees in being more uniform; there are fewer large pores 

 and less conspicuous medullary rays. 



The resinous sap, which is present in all parts of these plants, collected from 

 many species and by different methods, is the source of a variety of resins, turpen- 

 tines, tars, and pitches; the last two are considerably altered products owing to 

 the process of extraction by various forms of destructive distillation. Essential 

 oils are also secured from a number of them, usually from the leaves and young 

 twigs or cones, or in some instances from the wood. These are used in the arts 

 and in medicine. The large seeds of some pines of the northern hemisphere and 

 those of Araucaria imhricata Pavon, of South America, are nutritious and of con- 

 siderable importance as food. The astringent barks of many different species are 

 of great importance in tanning. 



The Pinaceas have either scaly or naked buds; their leaves are usually persistent, 

 narrow or needle-hke, or flat or scale-like, alternate, whorled, opposite or clustered. 

 The flowers are naked, there being no enclosing parts surrounding the ovules or 

 pollen-sacs, which are borne on the faces of scales, and these are aggregated in 

 catkin-Hke clusters, the pollen and ovules in separate catkins. The ovules develop 

 into seeds between the scales. The pistillate catkins grow into various forms of 

 dry or fleshy cones, constituting the fruit and from which the seeds are liberated 

 by the spreading of the scales, except in the berry-hke fruits of the Junipers where 

 these are united into a fleshy mass. The seeds are winged or wingless; the endo- 

 sperm is fleshy, mealy, or starchy, often resinous; the embryo is straight; the 

 cotyledons vary from 2 to 12, or more. The genera in our area are: 



Fruit dry, a simple cone. 



Scales of the cone numerous (or few in Larix); leaf-buds scaly. 



Cone-scales thick, woody; leaves needle-shaped, 2 to 5 in a sheath i. Finns. 



Cone-scales thin; leaves linear or filiform, fascicled or scattered. 

 Leaves fascicled on very short branchlets, deciduous. 2. Larix. 



Leaves scattered, persistent. 



Leaves jointed to short persistent woody stalks or sterigmata. 



Leaves 4-sided. 3. Picea. 



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