PIN ACE AE 27 



solitary or clustered, consisting of usually numerous spirally disposed bracted 

 scales. Ovules inverted, usually 2 at the base of each scale. Fruit a dry cone 

 formed by the accrescent scales of the pistillate anients. Seeds usually two at 

 the base of each scale, often samara-like, the wing a portion of the carpellary 

 scale. Endosperm copious, fleshy, or somewhat mealy. Cotyledons 2-16. 



Leaves several together, surrounded by a sheath at the base : cones maturing the second year. 

 ^Cone-scales with dorsal usually spine-armed appendages : leaves mostly in 2's or 3's. 



Leaves with 2 fibro-vascular bundles : seeds with elongated wings, these free from the scales, and 



attached to the seeds when they fall. 1. PINUS. 



<* Leaves with 1 fibro-vascular bundle : seeds with narrow or rudimentary wings, 



the ( se adnate to the scales when the seeds fall. 2. CARYOPITYS. 



<rCone-scales with inconspicuous terminal unarmed appendages : leaves in "5*5^- - 3. STROBUS. 

 Leaves solitary, without a sheath : cones maturing the first year. 

 Cones drooping : bracts shorter than the scales. 



Leaves 4-sided or nearly terete, spreading : anther-sacs opening lengthwise. 4. PICEA. 



Leaves flat, apparently 2-ranked : anther-sacs opening transversely. 5. TSUGA. 



Cones erect : bracts longer than the scales. 6. ABIES. 



1. PINUS L. 



Rigid monoecious evergreen trees or rarely shrubs, of great economic importance. 

 Leaves needle-like, 2-3 together or rarely more, each with 2 fibro-vascular bundles, the 

 clusters surrounded at the base by a thin persistent sheath, spreading in all directions. 

 Staminate aments elongated, at the ends of branchlets of the preceding year. Anthers 

 2-celled, opening longitudinally. Pollen-grains of 3 cells, the 2 lateral cells empty. Pistil- 

 late aments globose or slightly elongated, just back of the terminal bud, or on the young 

 twigs : scales crowded. Cones maturing the second year : scales at length hard and spread- 

 ing, each appendaged below the apex, usually spine-tipped. Seeds samara-like. The 

 plants flower in the spring, 



Scales of the pistillate aments stout, each with a short tip which scarcely equals the body in length. 

 Cones over 7 cm. long. 



Cones 16-25 cm. long, the spines of the scales stout and strongly recurved : staminate aments over 



5 cm. long : seed-wing over 4 cm. long. 1. p. palustris. 



Cones 8-14 cm. long, the spines of the scales small, not recurved : staminate 



aments less than 5 cm. long : seed-wing less than 4 cm. long. 

 Leaves not glaucous : cone of an ovoid type when open, flat or depressed 



at the base : seed-wing 2.5-3 cm. long. 2. P. Elliottii. 



Leaves glaucous : cones of a cylindric or conic-cylindric type when open, 



rounded at the base : seed-wing 1.5^2 cm. long. 

 Appendage of the cone scale very thick at the apex, projecting littlefif 



at all beyond the spine. 3. P. Taeda. 



Appendage of the cone-scale thin at the apex, projecting far beyond the 



spine. 4. P. heterophylla 



Cones less than 7 cm. long. 



Cones ovoid or globular-ovoid when closed : leaves 15-25 cm. long, about 2 



mm. wide. 5. P. serotina. 



Cones narrowly conic when closed : leaves 4-12 cm. long, about 1 mm. wide. 

 Cone-scales readily opening, each with a slender or minute spine towards 

 the front of the appendage, the spine sometimes deciduous or obsolete. 

 Cones mainly less than 5 cm. long : scales of the staminate aments erose- 



toothed at the apex : bark of the trunk relatively close and smooth. 6. P. glabra. 

 Cone mainly over 5 cm. long: scales of the staminate amentsj entire : 



bark of the trunk very rough and shaggy. 7. P. echinata. 



Cone-scales tardily opening or permanently closed, each with a'stout spine 



at the middle or towards the back of the appendage. 8. P. clausa. 



Scales of the pistillate aments slender, each with a subulate tip several times the 



length of the body. 



Cones conic when closed, ovoid when open : twigs glaucous. 9. P. Virginiana. 



Cones ovoid when closed, globose-ovoid or depressed when open ; twigs yellow. 

 Scales of the pistillate aments recurved : appendages of the cone-scales rela- 

 tively thin ; spine slender, more or less recurved. 10. P. rigida. 

 Scales of the pistillate aments ascending : appendages of the cone-scales very 



thick ; spines stout, more or less incurved. 11. P. pungens. 



1. Pinus palustris Mill. A tree of great economic importance, reaching a height of 

 40 m. and a maximum trunk diameter of 1.5 m., with few irregular spreading branches 

 near the top, the bark separating into large thin plates. Leaves typically 3 in a sheath, 

 20-40 cm. long, bright green, plumosely crowded at the tips of the branches, partially 

 drooping: sheaths 2-3 cm. long : staminate aments 5.5-8 cm. long : cones 16-25 cm. long, 

 narrowly conic when closed, broadly conic when open, often slightly curved, each scale 

 armed with a stout recurved spine : seed 12-13 mm. long, the wing 4.5-5 cm. long. [P. 

 australis Michx. ] 



In sandy soil, southeastern Virginia to Florida and Texas, locally inland to the foothills of Georgia 

 and Alabama. GEORGIA PINE. YELLOW PINE. LONG-LEAF PINE. 



2. Pinus Elliottii Engelm. A tree resembling P. palustris in habit, but smaller. 

 Leaves 2 or 3 in a sheath, 18-30 cm. long, bright green : sheaths about 1.5 cm. long : stami- 



