358 A HANDBOOK OF CONIFERS 



lanceolate entire or fringed in margin, and soon deciduous, except 

 the basal portion ; (c) Adult leaves, needle-like, persistent 2 or 

 more years, borne in clusters usually of 2, 3, or 5, according 

 to species, sometimes more in luxuriant plants, margin often 

 minutely toothed, the section semi-circular in the two-leaved 

 species, triangular in three- to five -leaved species ; fibro -vascular 

 bundle branched or simple; resin canals 2 or more, varying in 

 position.^ Sheath enclosing the leaf-bundles persistent ; decidu- 

 ous or partly so. The leaves when bruised emit a pungent odour 

 owing to the hberation of an oleo-resin rich in oil of turpentine. 



Male and female flowers appearing on the same tree and borne 

 during late spring and early summer. Male flowers yellow or 

 reddish, produced in groups of cylindrical cones round the base of 

 the young shoot ; their presence in winter being noticeable by a 

 distinct swelling around the base of the bud. The male flower con- 

 sists of numerous overlapping, stalkless, two-celled anthers, with 

 a crest-Hke roundish connective. Female flowers in cones usually 

 terminal or subterminal, but occasionally borne at irregular inter- 

 vals on the young shoots, composed of two series of scales, very 

 minute bracts which disappear in the ripe cone and large ovuli- 

 ferous scales, each of the latter bearing two pendulous ovules. 

 The scales open to receive the wind- distributed pollen in the 

 first year and close immediately afterwards, actual fertilization 

 of the ovule, i.e. the arrival of the pollen tube at the embryo 

 sac, not occurring until May or June of the following year, when 

 the cone rapidly increases in size, usually ripening at the end of 

 the second year, but in P. Pinea and P. leiophylla not maturing 

 untn the third autumn. The male flowers shrivel and fall soon 

 after the dispersal of the pollen. Mature cones very variable 

 in outline, symmetrical or oblique, the scales thin, or thick and 

 woody. Exposed part of each scale thickened and showing the 

 apex of the growth of the first year as a terminal or dorsal pro- 

 tuberance or scar called the umbo, which is often provided with a 

 prickle or stout hook. The cones of most species open their scales 

 when ripe and release the seeds, but in a few species the scales 

 remain closed and the seeds are Hberated by the cones falling and 

 rotting or by squirrels and other animals in search of food. In some 

 species the cones remain on the trees unopened for many years, 

 the scales ultimately separating when scorched by forest fires. 



Seeds nut-like, the kernel being surrounded by a shell (testa) 

 of varying hardness. In many species each seed is furnished with 

 a wing which aids in dispersal, but in other species the wing is 

 rudimentary or absent. 



The wood is fairly imiform in character, with the early (spring) 



^ The resin canals may be : — 1. Marginal against the hypoderm ; 2. Internal 

 against the endoderm ; 3. Medial in the green tissue ; 4. Septal, touching both 

 endoderm and hypoderm. 



