SUMMER KEY TO THE SPECIES OF PINUS
| a. | Leaves 5 in a cluster; cones 4-10 inches long. | P. strobus, p. [7]. | ||
| aa. | Leaves 2 in a cluster; cones less than 4 inches long. | |||
| b. | Leaves 1-3 inches long. | |||
| c. | Leaves about 1 inch long, divergent; cones sessile, pointingforward towards the tip of the branch, persistent10-15 years, opening very unevenly. | P. banksiana, p. [9]. | ||
| cc. | Leaves 1-1/2-3 inches long, slightly divergent; cones stout-stalked,pointing away from the tip of the branch,maturing in second season, opening evenly. | P. sylvestris, p. [13]. | ||
| bb. | Leaves 3-6 inches long. | |||
| c. | Bark of trunk red-brown; cones maturing in secondseason, about 2 inches long; cone-scales thickened at theapex, but unarmed. | P. resinosa, p. [15]. | ||
| cc. | Bark of trunk gray to nearly black; cones maturing infirst season, 2-3 inches long; cone-scales thickened at theapex and topped with a short spine. | P. laricio austriaca, p. [11]. | ||
WINTER KEY TO THE SPECIES OF PINUS
| a. | Leaves 5 in a cluster; cones 4-10 inches long. | P. strobus, p. [7]. | ||
| aa. | Leaves 2 in a cluster; cones less than 4 inches long. | |||
| b. | Leaves 1-3 inches long. | |||
| c. | Leaves about 1 inch long, divergent; cones sessile, pointingforward towards the tip of the branch, persistent10-15 years, opening very unevenly. | P. banksiana, p. [9]. | ||
| cc. | Leaves 1-1/2-3 inches long, slightly divergent; cones stout-stalked,pointing away from the tip of the branch,maturing in second season, opening evenly. | P. sylvestris, p. [13]. | ||
| bb. | Leaves 3-6 inches long. | |||
| c. | Bark of trunk red-brown; cones maturing in secondseason, about 2 inches long; cone-scales thickened at theapex, but unarmed. | P. resinosa, p. [15]. | ||
| cc. | Bark of trunk gray to nearly black; cones maturing infirst season, 2-3 inches long; cone-scales thickened at theapex and topped with a short spine. | P. laricio austriaca, p. [11]. | ||
White Pine
