PINACEAE (PINE FAMILY) 63 



Tribe II. TAXODiEAE. Fertile flowers of several spirally arranged imbricated scales without 

 bracts, becoming a globular woody cone. Ovules 2 or more at the base of each scale, erect. 

 Leaves linear, alternate ; leaf-buds not scaly. 



6. Taxodium. Seeds 2 to each scale. Leaves 2-ranked, deciduous. 



Tribe III. CUPRESSEAE. Scales of the fertile flower few, decussately opposite or ternate, becom- 

 ing a small closed cone or sort of drupe. Ovules 2 or more in their axils, erect. Cotyledons fe 

 (rarely more). Leaves decussately opposite or ternate, usually scale-like and adnate, the earlier 

 free and subulate ; leaf-buds not scaly. 



* Monoecious ; fruit a small cone ; leaves opposite and more or less 2-ranked. 



7. Chamaecyparis. Cone globose ; scales peltate. Seeds 1 or 2, narrowly winged. 



8. Thuja. Cone pendulous, ellipsoid, of 8-12 imbricated scales. Seeds 2, 2-winged. 



* * Dioecious ; fruit berry -like, with bony ovate seeds. 



9. Juniperus. Fruit-scales 3-6, coalescent. Foliage not 2-ranked. 



1. PlNUS [Tourn.] L. PINE 



Filaments short ; connective scale-like ; anther-cells 2, opening lengthwise. 

 Pollen of 3 united cells, the 2 lateral ones empty. Fruit a cone formed of 

 the imbricated woody scales, which are persistent, spreading when ripe and dry ; 

 the 2 nut-like seeds partly sunk in excavations at the base of the scale. Cotyle- 

 dons 3-12, linear. Primary leaves thin and chaff-like, merely bud-scales ; from 

 their axils immediately proceed the secondary needle-shaped evergreen leaves, 

 in fascicles of 2 to 5, from slender buds, some thin scarious bud-scales sheathing 

 the base of the cluster. Leaves when in pairs semicylindrical, becoming chan- 

 neled ; when more than 2 triangular ; their edges in our species serrulate. 

 Blossoms developed in spring ; the cones maturing in the second autumn. 

 (The classical Latin name.) 



Leaves 5 in a fascicle ; cone-scales thin . . . . . .1. P. Strobus. 



Leaves 2-3 in a fascicle ; cone-scales thickened at the end. 

 Cone-scales unarmed. 



Leaves 9-16 cm. long; sheath 8-21 mm. long 10. P.resinosa. 



Leaves 4.5-6 cm. long ; sheath 2-5 mm. long ; resin-ducts in each leaf 



numerous, peripheral or nearly so 9. P. sylvestris. 



Leaves 1.5-4 cm. long ; resin-ducts mostly 2, deeply embedded in the leaf- 

 tissue 7. P. Banksiana. 



Cone-scales armed with a sharp dorsal spine or prickle. 



Cone very large, 15-25 cm. long 11. P. palustris. 



Cone 8-12 cm. long. 



Spine of cone-scales stout, 5-6 mm. long 5. P.pungens. 



Spine of cone-scales smaller, 1-3 mm. long. 

 Leaves somewhat rigid, 1.8-3 mm. broad. 



Leaves in 2's, 1.5-4 cm. long 7. P. Banksiana. 



Leaves in 3's, 5-12 cm. long 8. P. rigida. 



Leaves in 3's, 15-25 cm. long 4. P. serotina. 



Leaves flaccid, 0.7-1.5 mm. broad. 

 Old cones when open subcylindric-ovoid, about 10 cm. long, usually 



shining 2. P. Taeda. 



Old cones when open broadly ovoid, 4-7 cm. long, dull. 



Spine of cone-scale 2-3 mm. long ; leaves in 2's, 4-8 cm. long . 6. P. virginiana. 

 Spine of cone-scale minute, about 1 mm. long ; leaves in 2's or 



8's, 7-13 cm. long 8. P. echinata. 



1. P. Strbbus L. (WHITE P.) Tree 20-50 m. high ; leaves in 5's, very 

 slender, glaucous ; sterile flowers oval (8-10 mm. long), with 6-8 involucral 

 scales at base ; fertile catkins long-stalked, cylindrical ; cones narrow, cylindri- 

 cal, nodding, often curved (1-1.5 dm. long); seed smooth; cotyledons 8-10. 

 Nfd. to Pa., along the mts. to Ga., west to Man. and e. la. 



2. P. Tadda L. (LOBLOLLY or OLD-FIELD P.) Leaves long (14-23 cm.), in 

 3's or sometimes 2's, with elongated sheaths, light green ; cone-scales tipped 

 with a stout incurved spine. Wet clay, or dry sandy soil, s. N. J. to Fla., near 

 the coast, thence to Tex. and Ark. A tree 15-45 m high , staminate flowers 

 slender, 5 cm. long, usually with 10-13 involucral scales ; seeds with 3 strong 

 rough ridges on the under side. 



