1. Leaves in clusters of 2 or more.
2. Leaves in clusters of 5 _Pinus strobus_
2. Leaves in clusters of 2-3.
3. Leaves in clusters of 2.
4. Most or all the leaves less than 3 inches long, usually
twisted.
5. Leaves up to 1½ inches long; sheath at base of leaves not
longer than ⅛ inch _Pinus banksiana_
5. Leaves 2-3 inches long; sheath at base of leaves at least ⅓
inch long _Pinus sylvestris_
4. Most or all the leaves longer than 3 inches, rarely twisted.
6. Leaves mostly less than 5 inches long; cone-scale with a
small spine _Pinus echinata_
6. Leaves mostly more than 5 inches long; cone-scale without a
spine _Pinus resinosa_
3. Leaves in clusters of 3.
7. Leaves flexible, mostly less than 5 inches long; sheath at
base of leaves about ¼ inch long _Pinus echinata_
7. Leaves stiff, mostly more than 5 inches long; sheath at base
of leaves about 1 inch long _Pinus taeda_
1. Leaves solitary, of 2 types, some of them scale-like and about ⅛
inch long, some of them needle-like and up to ⅓ inch long
_Juniperus virginiana_