156 American Midland Naturalist Monograph No. 7 



18. Cultivated shrubs; leaves oval 2-6 cm wide, the margins 

 somewhat undulate, crenate to entire, glaucous, reticu- 

 late, grayish pubescent; chiefly staminate; rarely per- 

 sisting near old dwellings; native of Eur. Mar. -April. 



Goat Willow .S". caprca L. 



18. Native shrubs. 



19. Pistillate catkins 2-4 cm long, becoming 4-6 cm long 

 in fruit; mature capsules 7-10 or 12 mm long; 

 pedicel shorter than the scale; leaves elliptical to 

 obovate, glabrous or nearly so at maturity, glaucous 

 beneath; tall shrubs (2-7 m high) ; wet ground, 

 local. Apr. -May. Pussy Willow [S. erioccphala 

 Michx. ; S. prinoidcs Piu'sh; S. discolor var. lati- 



folia Anders.] .S. discolor Muhl. 



19. Pistillate catkins 1.5-2 cm long, becoming 2-4 cin 

 long in fruit; mature capsule 6-9 mm long; pedicel 

 equalling or slightly longer than the scale; leaves 

 linear-oblanceolate, pubescent beneath; low shrubs 

 of sandy or clayey soil, common. Apr. -May. 

 Prairie Willow [S. tristis Ait.] S. Inanilis Marsh. 



70. Ulmaceae Mirb. — Elm Famil 



v 



1. Leaves with 1 principal vein from the base, the lateral veins straight, 

 parallel, usually more than 10 pairs; flowers in clusters on twigs of the 

 preceding season; twigs with solid pith. 

 2. Flowers appearing before the leaves; fruit a 1 -seeded, flat, thin-winged 



samara; leaves usually doubly serrate 1. Ulmus 



2. Flowers appearing with the leaves; fruit nut-like, nmricate ; leaves simply 



serrate 2. Planer a 



1. Leaves (at least when mature) with 3-5 veins from the base, the lateral 

 veins curved, fewer than 10 pairs; flowers borne on the twigs of the 

 season, appearing with the leaves; twigs with chambered pith; fruit a 

 drupe; bark corky-ridged 3. Celtis 



1. Ulmus L. — Elm 



1. Flowers drooping, on slender pedicels; calyx not ciliate; leaves 

 glabrous or nearly so above ; nut scabrous. 

 2. Branches not corky-winged; buds glabrous or nearly so; fruit 

 glabrous except the ciliate margins; woods, common. Apr. 



American or White Elm U. amcricana L. 



2. Branches (at least some of them) usually more or less corky- 

 winged; fruit pubescent. 

 3. Buds pubescent; leaves 5-13 cm long; flowers racemose; 

 woods in the n. half of the state. Apr. -May. Rock Elm 



[U . raccmosa Thomas, non Borkh.] U. thomasi Sarg. 



3. Buds glabrous or puberulent, not ciliate; leaves 2-8 cm long; 

 flowers fascicled; hillsides, cliff's, ridges; s. 111. Mar-Apr. 

 Winged Elm U. alala Michx. 



