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Flora of the Carolinas and Virginia, Working Draft of 1 January 1997 -- Gymnosperms Alan S. Weakley.
Copyright - Alan S. Weakley, 1998, 1999. All Rights Reserved.


Pinus Linnaeus (Pine)

References: Kral in FNA (1993), Duncan & Duncan (1988).

Note that young saplings generally have shorter needles than larger saplings and mature trees; measurements in the key are those of mature trees.

Main Key

1. Needles 5 in each bundle; each needle with 1 vascular bundle..... P. strobus
1. Needles 2-3 (-4) in each bundle; each needle with 2 vascular bundles.....2 3. Needles in bundles of 3, or 2 and 3, or 3 and 4 (predominantly or at least substantially in 3's).....4
3. Needles in bundles of 2 only.....9

5. Needles 3-7 cm long; prickles on cones 3-8 mm long, stout (more than 1 mm wide at base of prickle).....P. pungens
5. Needles 5-30 cm long; prickles on cones 1-3 mm long, slender (less than 1 mm wide at base of prickle).....6

7. Cones distinctly longer than broad when open or closed, 5-13 cm long; needles mostly (10-) 12-23 (-28) cm long, 0.7-1.5 mm wide; buds not resinous (or only slightly so); trunks not producing adventitious sprouts (epicormic sprouting).....P. taeda
7. Cones about as broad as long, 3-6 cm long; needles (4-) 7-16 (-20) cm long, 1.5-2.0 mm wide; buds resinous; trunks commonly producing adventitious sprouts (epicormic sprouting), especially in response to fire......8

9. Needles stout, 1.5-2 mm wide.....10


9. Needles slender to somewhat stout, 0.5-1.2 mm wide.....11

11. Needles 10-17 cm long; branches brittle; spring shoots with a single node, with 1 whorl of branches; [trees of the north, sometimes planted in our mountains] P. resinosa
11. Needles 2-13 cm long; branches flexible; spring shoots usually with several nodes (several whorls of branches); [trees of various habitats].....12 13. Anthers yellow; bark tight, closely ridged, not sloughing off, reminiscent of a hardwood; tip of seed cone scales with a faint horizontal ridge and a minute, deciduous prickle; [native trees of mesic to fairly wet, fertile soils] P. glabra
13. Anthers dark orange; bark flaky, the laminated layers sloughing off in a manner typical of a pine; tip of seed cone scales with a conspicuous horizontal ridge and a short, stout prickle; [non-native trees of xeric sands] P. clausa

Auxiliary Key to common pines of the Piedmont

1. Needles 12-25 cm long, predominantly in bundles of 3; winter buds more than 1 cm long; cones 6-15 cm long, falling soon after releasing seed; bark plates thick, without crater-like blisters.....P. taeda
1. Needles 2-13 cm long, predominantly in bundles of 2; winter buds less than 1 cm long; cones 3-7 cm long, persisting on trees for several years after releasing seed; bark plates thin, with or without crater-like blisters.....2