KEY TO THE GENERA OF NEBRASKA TREES 



A. Leaves needle-like, awl-shaped, or scale-like, mostly evergreen 



1. Leaves needle-like, solitary, not clustered 



a 1 Leaves scattered in a bristly manner on all sides of the twigs, 

 4-sided or angled, harsh; leafless twigs very rough; buds 

 scaly Spruce, p. 13. 



a 2 Leaves usually in 2 opposite ranks on the twigs, flat, soft; 

 leafless twigs comparatively smooth; buds resinous or waxy 



Fir, p. 31. 



2. Leaves scale-like or awl-shaped, small, blunt or sharp-pointed, 

 divergent or appressed, closely clustered 



a 1 Leaves scale-like, very small, blunt, flattened; twigs flattened; 

 cones small, composed of few, light brown, woody scales; tree 

 bright, yellow green Arbor Vitae, p. 33. 



a 2 Leaves awl-shaped, or some of them scale-like, often both 

 kinds on the same tree; cone a small, bluish berry; tree dark, 

 bluish green Juniper, p. 35. 



3. Leaves needle-like, in clusters of 2 to many 



a 1 Leaves in 2-, 3- or 5-leaved clusters, with a shallow sheath 

 at the base; persistent for several years; foliage generally 

 rather coarse Pine, p. 13. 



a 2 Leaves on all twigs except the current growth in clusters of 

 ten to more, on short, very stubby branches; leaves on current 

 growth single and scattered, all deciduous in autumn; foliage 

 rather soft Tamarack, p. 25. 



B. Leaves broad and flat, not needle-like, awl-shaped or scale-like, all 

 deciduous in autumn or winter in our climate 



1. Leaves simple, i. e., not compound or divided into leaflets 



a 1 Leaves opposite or in whorls about the twigs 



b 1 Margin of leaf finely serrate, entire or rarely toothed or 

 lobed 

 c 1 Leaf large, entire or rarely shallowly lobed, heart- 

 shaped, whorled; fruit a long slender pod 



Catalpa, p. 15. 



c 2 Leaf smaller, finely serrate, not heart-shaped; fruit 



fleshy, plum-like Black Haw, p. 163. 



b 2 Margin of leaf distinctly and regularly lobed or cut, the 



lobes coarse or fine Maple, p. 15. 



a 2 Leaves alternate on the twigs, never opposite 



b 1 Margin of leaf entire or merely wavy, not toothed or lobed 

 c 1 Leaves narrow, usually about V 2 inch wide, from 2 to 

 4 inches long, very silvery on the lower surface 



Russian Olive, p. 161. 

 c 2 Leaves much larger, 2 to 3 inches wide, 3 to 6 inches 

 long, not at all silvery 

 d 1 Twigs thorny, juice milky Osage Orange, p. 105. 

 d 2 Twigs not thorny, juice not milky 



Pawpaw, p. 111. 

 c 3 Leaves very broad, often as broad as long, heart- 

 shaped, smooth; flowers bright pink Red Bud, p. 133. 



b 2 Margin of leaf finely or coarsely toothed 



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