Proceedings of the Ohio State Academy of Science 117 



5. Leaves slender, 2^-5 in. long; buds not very resinous; prickles of the 

 ovuliferous scales short and small. P. echinata. 



5. Leaves stout, 1^-2^ in. long; buds very resinous; prickles of the 



ovuliferous scales long and stout. P. virginiana. 



6. Leaves 1-4 in. long, grayish-green or light green; ovuliferous scales 



without or with a small prickle, or with a thick point or spine. 7. 



6. Leaves 4-6 in. long, dark-green; ovuliferous scale without a spine 



or prickle, or sometimes with a very small prickle. 9. 



7. Ovuliferous scale without a spine or prickle when mature but with 



a minute central point ; leaves i-li- in. long, curved ; resin ducts 

 parenchymatous. P. divaricata. 



7. Ovuliferous scale with a thick point or spine. 8. 



8. Leaves 2-^-4 in. long, light green; twigs orange or orange brown; 



resin ducts parenchymatous ; carpellate cones ovoid. 3-5 in. long. 

 P. pungeiis. 



8. Leaves 1-1-2-J- in. long, grayish-green; twigs dull greenish-yellow or 



greenish-brown ; resin-ducts peripheral ; carpellate cones ovate- 

 conic, 2-3 in. long. P. silvestris. 



9. Carpellate cones terminal or subterminal, oval-conic; ovuliferous 



scales pointless when mature. P. resinosa. 

 9. Carpellate cones lateral, ovoid-conic; ovuliferous scale with a small 

 prickle. P. laricio. 



1. Pinus strobus L. White Pine. A large tree with 

 nearly smooth bark, except when old ; branches horizontal in 

 whorls. (Jften forming dense forests. Wood soft and straight- 

 grained ; used in enormous quantities for building purposes. One 

 of the most valuable timber trees in the world. Has been more 

 extensively used in America for lumber than any otlier tree. 

 Newf. to Man., south along the Allegh. to Ga. and to Ohio, 111. 

 and la. 



2. Pinus resinosa Ait. Red Pine. A tall tree with 

 reddish bark. Wood rather hard but not very durable. Tur- 

 pentine is obtained to a limited extent from this species. A tree 

 of rapid growth. Newf. to Man., Mass., Penn., and Minn. 



3. Pinus divaricata (Ait.) Gord. Jack Pine. A slender 

 tree with spreading branches, the bark becoming flaky. Wood 

 light and rather soft. In sandy soil. N. B. and N. W. Terr., 

 south to Me., N. Y., 111., and Minn. 



4. Pinus virginiana Mill. Scrub Pine. A slender, 

 usually small tree with spreading or drooping branches ; the old 



