16 KEY AND FLORA 



armed with a slender, straight or recurved prickle. On dry, sandy- 

 soil ; wood light, soft, weak, and of little value.* 



5. P. sylvestris L. Scotch Ppne (wrongly called Scotch Fir). A 

 medium-sized tree, with the older bark reddish and scaly. Leaves in 

 twos, lh-2h in. long. Cones rather small and tapering (Fig 1, 1, c). 

 Cultivated from Europe. 



6. P. resinosa Ait. Red Pine, Norway Pine. A tall, rather 

 slender tree, with bark reddish-brown and moderately smooth. 

 Leaves in twos, slender, and 5-6 in. long. Cones borne at the ends 

 of the branches, smooth, about 2 in. long. A valuable timber tree, 

 which often grows in small, scattered clumps; wood firm, pale red, 

 and not very resinous ; used in house and bridge building, and for 

 masts and spars. 



7. P. palustris Mill. Long-Leaved Pine. A large tree ; bark 

 thin-scaled, wood very resinous, old trees with only a few spreading 

 branches near the top. Leaves in threes, 10-15 in. long. Sheaths 

 1-1 1 in. long, crowded near the ends of very scaly twigs. Staminate 

 catkins 2-3 in. long, bright purple, conspicuous. Cones terminal, 

 ellipsoid-conical, 6-10 in. long, diameter 2-o in. before opening, 4-6 

 in. when fully opened ; scales much thickened at the apex and armed 

 with a short recurved spine at the end. The most common tree in the 

 pine barrens ; wood hard, strong, and durable, especially valuable for 

 floors and inside work.* 



II. PICEA Link 



Sterile flowers generally axillary (sometimes terminal), 

 borne on the twigs of the preceding year. Fertile flowers 

 terminal. Fruit a nodding, thin-scaled cone, ripening in the 

 first autumn. Leaves evergreen, needle-shaped, four-angled, 

 scattered or spirally arranged. 



1. P. mariana BSP. Black Spruce. A small tree, usually only 

 20 or 30 ft. high, often less. Leaves strongly 4-angled, bluish-green, 

 and glaucous, ^-| in. long. Cones ovoid, pointed, ^-1+ in., usually 

 about 1 in. long, persisting sometimes for 20-30 years. Wood of 

 little value except for paper pulp. The tree is especially abundant 

 northward and is of common occurrence in peat bogs. 



2. P. rubra Dietrich. Red Spruce. A large tree, 70-80 or even 

 100 or more feet high, of strict conical habit. Leaves dark green or 

 yellowish and glossy, ^-f in. long. Cones ovoid-oblong, acute, usually 

 l|-2 in. long, mostly falling the first year. This is the principal 

 timber spruce of the northeastern United States, and furnishes much 

 rather tough lumber for use in floor joists, scantling, and similar 

 purposes. 



