
Manual of the Vascular Flora of the Carolinas - Radford, Ahles, Bell
Copyright - UNC Press 1998, 1999. All Rights Reserved.
1. PINUS L. PINE
Monopodial trees. Primary leaves mere scales, subtending minute branchlets, each branchlet (except on juveniles) bearing a fascicle of 2 or more needle-shaped, evergreen foliage leaves, the base of the fascicle surrounded by one or more scarious sheathing leaves, the whole fascicle of foliage leaves with sheathing leaves and the stubby branchlet falling together after 2 or more years; male cones in clusters at the base of the current year's growth of some of the branches, more abundant on the lower ones, each male sporophyll with 2 sporangia attached the length of the sporophyll, and opening longitudinally; pollen winged; female cones more abundant on upper branches; end of the sporophyll in most species thickened and with an umbo or spine, maturing in the fall of the second year.
- Leaves 5 in a fascicle, cone scales thin apically..... 1. P. strobus.
- Leaves less than 5 in a fascicle; cone scales thick apically.
- Leaves mostly 3 in a fascicle.
- Leaves more than 25 cm long; mature cones mostly more than 15 cm long..... 2. P. palustris.
- Leaves mostly less than 25 cm long; mature cones less than 15 cm long.
- Cones longer than broad, not top-shaped.
- Cones reddish brown glossy. leaves dark green, glossy, some in 2s.....3. P. elliotii.
- Cones brown, not glossy; leaves yellow-green, not glossy, very rarely in 2s.....4. P. taeda
- Cones about as broad as long, top-shaped.
- Leaves mostly 2 in a fascicle.
- Leaves stiff; prickles on cone stout..... 7. P. pungens.
- Leaves pliable; prickles on cone slender weak.
- Leaves not twisted: bark of branches rough..... 8. P. echinata.
- Leaves twisted hark of branches smooth.
- Leaves usually more than 6 cm long; bark or trunk dark, ridged..... 9. P. glabra.
- Leaves usually less than 6 cm long; bark of trunk light brownish-orange, in thin plates..... 10 P. virginiana.