Proceedings of the Ohio State Academy of Science 119 



1. Carpellate cones rather large, f-la in. long; ovuliferous scales finely 

 tomentose on the back. L. decidua. 



I. Larix laricina (DuRoi)Koch. Tamarack. A slender 

 tree with close or at length scaly bark. Wood hard, durable, and 

 very strong; used in ship-building, for railroad ties, posts, and 

 telegraph poles. In swamps and about the margins of lakes.. 

 Newf. to N. W. Terr., south to Minn., Ind., Ohio, and N. J. 



*. Larix deci'dtia Mill. European Larch. A beautiful 

 tree with horizontal branches and drooping branchlets, conical in 

 shape when young; much cultivated in some parts of the United 

 States. The source of Venice turpentine. 



4., Picea Link. Spruce. 



Evergreen trees, conic in outline, with short linear 4-sided 

 leaves spreading in all directions ; the leaf scars on persistent 

 sterigmata. Carpellate cones pendulous. 



1. Carpellate cones 2^-6 in. long. P. excelsa. 



1. Carpellate cones f-2 in. long. '"2. 



2. Twigs and sterigmata of the leaves glabrous, glaucous; carpellate 



cones oblong-cylindric. P. canadensis. 



2. Twigs pubescent, brown; carpellate cones ovoid or oval. 3. 



3. Leaves not glaucous. P. mariana. 

 3. Leaves glaucous. P. brevifolia. 



1. Picea canadensis (Mill.) B. S. P. White Spruce. A 

 slender tree sometimes with a strong skunk-like odor. Leaves 

 light green, slender, -|-f in. long, very acute. An important tim- 

 ber tree with light and straight-grained wood. Newf. to Alaska, 

 south to Me., Mich., Black Hills, and Br. Col. 



2. Picea mariana (Mill) B. S. P. Black Spruce. A tree 

 with spreading branches and smooth or only slightly roughened 

 bark. Leaves not over f in. long, stout, green, closely covering 

 the twigs. Wood light and straight-grained ; used for paper 

 pulp, for general lumber and for masts and spars of ships. 

 Newf. to N. W. Terr., south to N. J., N. C, Mich., and Minn. 



3. Picea brevifolia Peck. Swamp Spruce. A small, 

 slender tree, or on mountains a shrub. Leaves nearly straight^ 



