where basal 2 side veins are slightly more conspicuous than others, and . . .
leaf juice=milky             >   mulberry genus Morus

leaf=asymmetric, narrow;  bark=very thick vertical ribs, looks covered with warts or puffy paint   >   hackberry Celtis occidentalis

leaf=asymmetric, broad, hairless                   >   American basswood Tilia americana
leaf=asymmetric, broad, undersurface=white + velvety   >   white basswood Tilia heterophylla

OR it does NOT (meaning the side veins are about equal size), and . . .

leaves=very narrow, twigs=slender+limber, buds covered by one scale, and . . .
leaf hairy white silky       >   white willow Salix alba
leaves and twigs droop   >   weeping willow Salix babylonica
leaf=∩ rounded               >   black willow Salix nigra
uppersurface=pale green, undersurface=paler   >   peach-leaved willow Salix amygdaloides

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plant terminology