ENUMERATION OF CONIFERS 295 



Var. argentea, Nels. Foliage silvery-white. 

 Var. aurea, Nels. Golden Deodar C. Foliage yellow. 

 Var. robusta, Carr. Longleaf Deodar C. With stouter branches and 

 more rigid leaves about 2 inches long. 



28. PINUS, L. PINE 



Evergreen trees with usually whorled branches, rarely shrubby; winter- 

 buds covered with imbricate scales: leaves of 2 kinds; the primary leaves are 

 spirally arranged and as they appear on young seedling plants and occasion- 

 ally on shoots from the old wood, are green and subulate, but commonly they 

 are reduced to small scarious bracts bearing in their axils the acicular, semi- 

 terete or triangular secondary leaves borne on an undeveloped branchlet 

 in clusters from 2-5, or occasionally more, rarely reduced to 1, surrounded at 

 the base by a sheath of 8-12 bud-scales: flowers monoecious; the staminate 

 ones axillary, clustered at the base of the young shoots, catkin-like, yellow, 

 orange, or scarlet, composed of numerous spirally arranged 2-celled anthers 

 with the connective enlarged and scale-like at the apex; the fertile flowers 

 lateral or subtcrminal, 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: cone subglobose to cylindric, with woody scales closely ap- 

 pressed 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 ex- 

 posed 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 species: other valuable characters are furnished by the structure of 

 the leaves, which contain either one or two fibro- vascular bundles and usually 

 two or more resin-ducts, which are either marginal (external or peripheral), 

 i. e., situated beneath the epidermis, or medial (parenchymatous), i. e., 

 inclosed by the tissue of the leaf; or internal, i. e., close to the fibro- vascular 

 bundles; some species, as P. Armandi, P. resinosa, P. sinensis, also P. 

 excelsa, P. Lambert iana, P. virginiana, have resin-ducts in 2 positions, either 

 marginal and medial or internal and medial, but such combinations are not 

 found in all the leaves of these species. Strengthening cells, i.e., cells with 

 thickened walls, are mostly present beneath the epidermis and often sur- 

 round the resin-ducts, sometimes also along the fibro-vascular bundles. 



