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. alha. 



Leaves green beneath. 2. P. deltoides. 



1. P. alba L. Silvee-leaf Poplak. A tree often 100° high : leaves 

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

 short pedicels. — Cultivated and spreading by suckers. Independence, 

 Eaytown. .April. 



2. P. deltoides 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 7" or less wide. 2. S. longipes. 



Leaves 6'''-14''' wide. 3. 8. amygdaloidea. 



Stamens two. 



Leaves on petioles 2"-4" long ; a tree. 4. S. alha viiellina. 



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



Catkins appearing before the leaves. 



Capsule densely pubescent. 6. S. kumilis. 



Capsule glabrous. , 7. S. cordata. 



1. S. nigra Marsh. Blaok 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 tvvioe 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 

 l//_7// 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 vltelllna (L.) Koch. White Willow. 50°-90° high: 

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

 serrulate : aments closely flowered : capsules almost sessile. — Adveutized 

 occasionally near Shefiield and Independence. April-May. 



