3 o PINE FAMILY 



Pinus Linne 1753 Pine 

 (L. p i n u s, the pine tree) 



Trees or sometimes shrubs with variously branched trunks; foliage 

 leaves evergreen, needle-like, in fascicles of two to five*, the young twigs 

 at first -without foliage leaves and clothed only with scattered spirally 

 arranged scales, the fascicles of foliage leaves appearing in the axils of 

 these scales, each fascicle at first surrounded by a sheath of similar scales 

 which may later fall away, or may be permanent, the whole fascicle even- 

 tually falling away from the branch at the end of several years' time ; 

 flowers monoecious, usually on separate branches, the staminate clustered 

 near the ends of the twigs, surrounding the base of a shoot of the cur- 

 rent season, consisting of an axis bearing numerous overlapping scale-like 

 stamens, each of which bears two pollen-sacs which open longitudinally; 

 tip of stamen knob-like, or with a small scale-like appendage, pollen 

 grains winged, the round grain bearing two air bladders which are about 

 equal in size to the grain proper; pistillate cones solitary or in small 

 groups, lateral or sub-terminal, the ovule-bearing scales of the young cones 

 longer than the bracts ; cones ripening in two or three years, woody, the 

 seed-bearing scales often much thickened at the outer end; cones open- 

 ing at maturity to scatter the seeds, or in some species remaining closed 

 for many years ; seeds usually winged, not resinous. 



About 70 species of the north temperate zone and the mountainous 

 parts of the northern tropics, most abundant in the warm temperate 

 . regions. Among the most valuable forest trees for timber and for their 

 various resinous products, turpentine, rosin, pitch, tar, etc. 



Key to the Species 



Two sub-genera are recognized. 



1. Strobus: The exposed portions of the cone scales but slightly 

 thickened, stamens nearly crestless, leaves in fascicles of five, the scaly 

 sheath usually quickly deciduous, wood soft. 



One species in Minnesota P. Strobus 



2. Pinaster: The exposed portions of the cone scales much thick- 

 ened, stamens bearing a crest-like scale, leaves in fascicles of 1-5 (2 in 

 all of our species), the scaly sheath usually persistent around the base 

 of the fascicle, wood often hard. 



Key to species of Pinaster growing in Minnesota, based on leaf struc- 

 ture. Leaves in all of our speck's semi-circular or crescentic in cross 

 section, and with two vascular bundles. 



•In a peculiar species of the southwestern United States there Is only one 

 foliage leaf in each fascicle. 



