68 SALICACEAE 



1. POPULUS L. 



Trees with broad leaves. Buds scaly, resinous covered. Filaments 

 distinct. Ovary sessile. Stigmas 2-4, elongated. Capsule 2-4-valved. 



Leaves white, tomentose beneath. 1. P. alba. 



Leaves green beneath. 2. P. deltoides. 



1. P. alba L. SILVER-LEAF POPLAR. A tree often 100 high : leaves 

 ovate-orbicular, sinuate toothed, white-tomeutose beneath : capsules on 

 short pedicels. Cultivated and spreading by suckers. Independence, 

 Raytown. April. 



2. P. deltoidea Marsh. COTTON- WOOD. 50-150 high : leaves broadly 

 deltoid, abruptly acuminate, crenulate : petiole laterally flattened : cap- 

 sules long-pedicelled. Common in river bottoms. April. 



2. SALIX L. WILLOW. 



Trees or shrubs with narrow leaves. Buds covered by a single scale. 

 Filaments distinct or united. Ovary sessile or short stipitate. Stigmas 

 2, short. Capsule 2-valved. 



Catkins appearing after the leaves. 

 Stamens three to five. 



Leaves green on both sides. 1. S. nigra. 



Leaves glaucous, whitened beneath. 



Leaves "1" or less wide. 2. S. longipes. 



Leaves 6 // -14 // wide. 3. 8. amygdaloides. 



Stamens two. 



Leaves on petioles 2 // -4 // long ; a tree. 4. 8. alba vitfUina. 



Leaves almost sessile : a shrub. * 5. S, interior. 



Catkins appearing before the leaves. 



Capsule densely pubescent. 6. S. humilis. 



Capsule glabrous. 7. S. cordata. 



1. S. nigra Marsh. BLACK WILLOW. 15-100 high : leaves lanceo- 

 late, long-attenuate, downy when young, at length green and glabrous 

 except on the veins beneath, serrulate : petioles l/'-S" long : fruiting 

 aments usually dense : capsules twice the length of their pedicels. 

 Common along streams. April-May. 



2. S. longipes Shuttlw. A shrub or small tree : leaves lanceolate, 

 long-acuminate, silvery-white and usually pubescent beneath, on petioles 

 I"-?" long : aments loosely flowered : capsules on pedicels of nearly their 

 own length. Eocky beds of streams throughout the western half, but 

 not abundant. April-May. 



3. S. amygdaloides Anders. Like S. longipes but with broader, long- 

 petioled, nearly glabrous leaves : stipules small : aments loose : capsules 

 on long filiform pedicels. Common along streams, especially in the 

 Missouri bottoms. April-May. 



4. S. alba vitellina (L.) Koch. WHITE WILLOW. 50-90 high: 

 leaves oblong-lanceolate, glabrous above when mature, whitish beneath, 

 serrulate : aments closely flowered : capsules almost sessile. Adventized 

 occasionally near Sheffield and Independence. April-May. 



