GROUPS OF PLANTS. 



79 



iiig; Red cedar {Junipcrus virginiana) (Fig-. 52) used in the 

 making of cigar boxes and lead pencils; balsam fir i^Abics bal- 

 sanica ) used in the manufacture of wood pulp. 



Py reason of the oleo-resinous constituents the woods of some 

 of the Coniferae are among the most durable known. A few 

 years ago Jeffrey examined a specimen of Sequoia Pcnhalloivii 

 which was obtained from auriferous gravels of the Miocene in 

 the Sierra Nevada Mountains and found it to be in a very perfect 



?iG. 51. Transverse section of the stalk of Juniperus Sa^ina at the point of attach- 

 ment of two leaves, ep, epidermis; s, stomata; h, hypodermis; pal, palisade cells; 1, bast 

 fibers; b, xylem; r, mechanical tissue; S, oil secreting gland or reservoir. After Mongin. 



State of preservation. Penhallow {loc. cit.) considers this to lie 

 the most ancient record of an uninfiltrated and unaltered wood. 

 Coleman, in 1898, found in the Pleistocene clays of the Don 

 Valley a specimen of red cedar {Junipcrus virginiana) which not 

 only possessed all of the external characteristics of this species 

 but when sawed emitted the aromatic odor of the bark. In the 

 Pleistocene deposits of the western Ignited States and Canada 

 are found more or less unaltered specimens of various species 

 of Juniperus, Pseudotsuga, Picea, and Larix. 



