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