SALICACEAE. 91 



Bracts incised : disk cup-like : stamens usually 10 or more, rarely 6-8 : stigmas elon- 

 gate and expanded : winter buds with several scales. 1. POPULUS 



Bracts entire : disk merely 1 or more axillary glands : stamens less 

 than 10 : stigmas short, not expanded : winter buds with 1 scale 

 each. 2. SALIX. 



1. POPULUS [Tourn.] L. Trees, the buds with several scales. Leaf- 

 blades palmately veined, relatively long-petioled. Stamens more than 10, or 

 rarely 6 or 8 : anthers purple or red. Ovary sessile. Stigmas dilated. Spr. 

 POPLAR. COTTONWOOD. 



Petioles much flattened laterally. 



Leaf -blades ovate or suborbicular : capsules conic, slender : scales pubescent. 



1. P. grandidentata. 

 Leaf -blades deltoid or somewhat reniform : capsules ovoid 



to subglobose, thick : scales glabrous. 



Stamens 6-8 : branches erect. 2. P. italica. 



Stamens 50 or more : branches spreading. 3. P. deltoides. 



Petioles terete or channeled. 



Leaf-blades glabrous or nearly so when mature, not lobed 4. P. candicans. 

 Leaf-blades persistently white-tomentose beneath, 3-5 



lobed. 5. P. alba. 



1. P. grandidentata Michx. Tree becoming 25 m. tall, the bark fissured: leaf- 

 blades ovate, 6-10 cm. long, sinuate-dentate: middle lobe of the ament-bracts 

 much shorter than the body : capsules 4-7 mm. long. N. S. Bather rare, in 

 woods. Sandstones and shales, schists. 



2. P. italica Moench. Tree with a fastigiate top, commonly 25 m. tall: leaf- 

 blades deltoid or subrhomboid, crenate or crenate-serrate : staminate aments 2-5 

 cm. long: stamens 6-8 1 : capsules 6-8 mm. long [P. dilatata Ait.]. S. Not 

 common, on roadsides and along streams. Nat. of Eu. LOMBARDY-POPLAR. 



3. P. deltoides Marsh. Tree becoming 45 m. tall, the top not fastigiate: leaf- 

 blades ovate to deltoid, acute or acuminate, serrate or crenate-serrate : staminate 

 aments 8-12 cm. long: stamens numerous: capsules 8-10 cm. long. N. M. 

 Eare, on roadsides and in fi'elds. Nat. southward and westward. NECKLACE- 

 POPLAR. 



4. P. candicans Ait. Tree sometimes 30 m. tall, the bark ridged: leaf -blades 

 broadly ovate, 6-15 cm. long, acuminate, crenate: staminate aments with 

 incised bracts: pistillate aments elongate, the flowers short-pedicelled : capsules 

 ovoid, 8-11 mm. long. M. Bather rare, on roadsides and in fields. Nat. of Eu. 

 BALM-OF-GILEAD. 



5. P. alba L. Tree becoming 35 m. tall, the bark pale, becoming rough: leaf- 

 blades ovate to suborbicular, 5-10 cm. long, white-tomentose beneath: staminate 

 aments 3-5 cm. long, the anthers purple: pistillate aments about twice as long 

 as the staminate : capsules conic. N. M. Eather common, on roadsides and in 

 waste places. Nat. of Eu. WHITE-POPLAR. SILVER-LEAVED POPLAR. 



2. SALIX [Tourn.] L. Shrubs or trees, the buds with a single scale. 

 Leaf-blades pinnately veined, relatively short-petioled. Stamens 2, or rarely 

 1-7 : anthers yellow or reddish. Ovary stipitate : stigmas not dilated. Spr. 

 WILLOW. 



Capsules glabrous, at least at maturity. 



Stamens 3-7 : filaments pubescent at the base : bracts yellow, caducous. 

 Pedicels 3-5 times as long as the glands. 



Stipules and petioles glandless. 1. 8. nigra. 



Stipules and petioles prominently glandular. 2. S. lucida. 



Pedicels about twice as long as the glands. 3. S. fragilis. 



Stamens 2. 



Filaments pubescent at the base: bracts caducous. 

 Pedicels 1-3 mm. long at maturity. 



Styles wanting: leaves with linear or linear- 

 lanceolate blades. 7. 8. interior. 



