BETULACEAE 69 



5. S. interior Rowlee. Sand-bar Willow. 2°-25° high : leaves 

 linear, remotely denticulate, glabrous, or silky-pubescent in the young 

 shoots : anients linear, cylindric, dense : capsules short-pedicelled, hairy 

 when young. — Extremely abundant on sand-bars along the Missouri River. 

 May-July. 



6. S. humilis Marsh. Low Willow. 2°-15° high : leaves oblanceo- 

 late, short-petioled, rugose-veined and more or less tomentose beneath, 

 with nearly entire, revolute margins : aments dense, sessile, V long, ovoid- 

 oblong: capsule short-pedicelled. —Prairies and barrens throughout. Often 

 abundant. March-April. 



7. S. cordata INIuhl. A shrub 5°-12° high, the twigs glabrous or 

 puberulent : leaves oblong-lanceolate, acuininate, serrate : stipules large : 

 pistillate aments lY-^Y long, linear : capsule 3-4 times the length of its 

 pedicel. — Along streams east of Independence, along Brush Creek, at 

 Kansas City, etc. March-April. 



Var. Missoiiriensis (Bebb) Mackenzie & Bush, n. comb. A shrub or 

 tree 10°-50° high, often forming a large trunk with blackish bark : 

 aments longer. — Common in rich soil along streams. Distinguished from 

 the type by being larger throughout, more robust and having black bark. 

 {S. 3Iissouriensis Bebb.) 



Family 30. BETULACEAE Agardh. 

 Trees or shrubs with alternate simple leaves and monoecious flowers 

 mostly in aments. Staminate flowers in long drooping aments, 1-3 to- 

 gether in axils of bracts, consisting of 2-10 stamens and no calyx (in 

 oursj. Pistillate aments spike-like or capitate with a 2-celled, 2-ovuled 

 ovary. Fruit a 1-seeded nut. 



Pistillate flowers in aments. 1. Osteya. 



Pistillate flowers capitate. 2. Corylus. 



1. OSTRYA Micheli. 



Small trees with very hard wood and leaves appearing after the flowers. 

 Staminate flowers without bractlets at base. Nut small, enclosed in the 

 large, inflated, oblong, sac-like bractlet. 



1. O. Virglniana (Mill.) Willd. Iron Wood. 50° or less high : 

 leaves oblong-ovate, petioled, sharply-serrate, strongly-nerved, slightly 

 downy beneath. — Common in woods throughout. April-May. 



2. CORYLUS Touin. Hazel Nut. 



Shrubs. Staminate flowers with two bractlets at ba?e. Bractlets of 

 pistillate flower two, enlarging in fruit and enclosing the ovoid, large, 

 bony nut. 



Involucral bracts long-beaked. 1. C. rostrata. 



Involucral bracts not beaked. 2. 0. Americana. 



