CONIFERS. (PINE FAMILY.) 431 



long, sometimes pubescent at maturity, like the branchlets. Fertile amenta 

 3' -4' long. 



The WEEPING-WILLOW (S. Babylonica, Tourn.), and the YELLOW WILLOW 

 or GOLDEN OSIEK (S. vitellina, Smith), are introduced species. 



2. POPULTJS, Tourn. COTTON-WOOD. POPLAR. ASPEN. 



Bracts of the aments toothed or lobed. Flowers from an oblique cup-shaped 

 disk. Stamens few or numerous, with the filaments free. Stigmas elongated, 

 2-parted. Trees. Leaves ovate or roundish, on long and often laterally com- 

 pressed petioles. Buds covered with imbricated, often resinous-coated scales. 

 Aments slender, drooping, appearing before the leaves. 



1. P. angulata, Ait. Branches thick, smooth, and sharply angled ; leaves 

 large, smooth, deltoid-ovate, acute or slightly acuminate, truncate at the base, 

 obtusely serrate with incurved teeth ; the conspicuous veins and compressed peti- 

 ole yellowish. Banks of rivers, Florida, and northward. March and April. 

 A large tree. Leaves 6' - 8' long, longer than the petiole. 



2. P. grandidentata, Michx. Branches terete; leaves round-ovate, 

 acute, sinuate-toothed, hoary-tomentose when young, like the branchlets, at 

 length smooth, scarcely longer than the slender compressed petiole; fruiting 

 aments elongated, pubescent. Low woods in the upper districts, and northward. 

 March and April. A middle-sized tree, with smooth gray bark. Leaves 3' 5' 

 long, and nearly of the same width. 



3. P. heterophylla, L. Branches terete; leaves ovate, mostly obtuse, 

 serrate, with obtuse, incurved teeth, rounded or with a small sinus at the base, 

 hoary-tomentose on both sides when young, like the nearly terete petioles and 

 branchlets, at length only on the veins beneath ; fruiting aments smooth. 

 River-swamps in the middle and upper districts, Mississippi to North Carolina, 

 and northward. March and April. A large tree. Leaves 3' -5' long. 



The LOMBARDY POPLAR (P. dilatata, Ait.), and the WHITE POPLAR (P. 

 alba, L.), are introduced species. 



SUBCLASS II. GYMNOSPERM^E. 



Ovules iiaked (not enclosed in an ovary), commonly sup- 

 ported by an open scale or leaf, and fertilized by the direct 

 application of the pollen. Cotyledons often more than two. 



ORDER 132. CONIFER^E. (PINE FAMILY.) 



Trees or shrubs, with branching stems, composed of glandular or disk- 

 bearing woody tissue without ducts, resinous juice, linear or needle-shaped 



