48 BOTANICAL GAZETTE [yuLy 
The pines are divided into the hard pines and the soft pines. The 
former are characterized by possessing dentate or reticulate tracheids — 
of the rays, and by having no tangential pits developed in the tracheids — 
at the end of the year’s growth. The soft pines, on the contrary, are 
supposed to possess marginal and interspersed tracheids of the rays — 
with unsculptured walls, and to have well-developed tangential pits in A 
the tracheids formed at the end of the year’s growth. The majority : 
of the hard pines and soft pines can easily be separated from — 
the remaining genera of the Pineae by the character of the pits in 
the lateral walls of the parenchymatous cells of the rays. These pits 
are very large and often polygonal, and quite distinct from the small 
round. pits of Picea, Larix, and Pseudotsuga. However, in the nut 
and foxtail pines above referred to, and in certain of the hard pines, 
we find a diminution in the size of the pits, which approaches the 
condition in the Picea type. 
PICEA | 
Picea has a wood with thick-walled epithelial cells in the resin 
canals and tangential pits in the summer tracheids. The pits in the 
lateral walls of the ray cells are small and round. The wood- 
enchyma is entirely absent. Spiral thickenings of the tracheids are | 
also absent, according to PENHALLow.* However, GOTHAN (0P. ctl, 
98) and other European authorities note their presence in the summe : 
wood alone. eee : 
LARIX 
The wood resembles Picea as regards the thick-walled chara 
of the resin canals, the presence of tangential pits in the sum 
tracheids, and the small size of the lateral pits of the ray cells; 
possesses well-developed wood-parenchyma upon the outer surlé 
of the summer wood. Spiral thickenings of the tracheids are pre 
only in the summer wood. : 
PSEUDOTSUGA 
The wood resembles Picea and Larix as regards thick-walled 
thelium, tangential pits of the summer tracheids, and form a 
of the pits of the ray cells. It also resembles Larix in having p@ 
chyma well developed upon the outer surface of the summer We 
The wood, however, is supposed to be quite distinct in having ¥ 
4 PENHALLOw, North American Gymnosperms 195. Boston. 1907- 
