1	"Leaves green "	2
1	"Leaves white flecked or yellow-green (ensure these are true cultivars, avoid diseased or autumn leaves) "	10
2	"Leaves rough above"	3
2	"Leaves smooth above"	6
3	"Leaves large, extremely rough above, widest above the centre, basal lobe covering leaf stalk and twig "	"Ulmus glabra"
3	"Leaves not widest above the centre, basal lobe not covering both leaf stalk and twig"	4
4	"Leaves roundish (see illustration)"	"Ulmus procera"
4	"Leaves broadly ovate to elongate "	5
5	"Leaves widest at or near the centre, margins widely separated where they join leaf stalk (see fig.); fruit with hairy margin (rare) "	"Ulmus americana"
5	"Leaves variously shaped, margins not widely separated where they join the leaf base; fruit without a hairy margin (common) "	"Ulmus ×hollandica"
6	"Bark generally orange-brown and scaly; leaves generally semi-evergreen, less than 5 cm long, marginal teeth simple "	"Ulmus parvifolia"
6	"Bark fissured, not orange-brown scaly; leaves deciduous, more than 5 cm long, marginal teeth multiple "	7
7	"Leaves mostly 5–7.5 cm long, leaf base more or less equal (rare) "	"Ulmus pumila"
7	"Leaf base distinctly unequal "	8
8	"Leaves mostly 5–9 cm long with straight short side (see illustration), waxy feel above, vein pairs mostly 10–13 "	"Ulmus minor"
8	"Leaves mostly more than 8 cm long, without a distinct straight side, vein pairs more than 13 "	9
9	"Leaves variable, margins not widely separated where they join leaf base; fruit without hairy margin (common) "	"Ulmus ×hollandica"
9	"Leaves widest at about the centre, margins widely separated where they join leaf stalk (i.e. base very unequal); fruit with hairy margin (rare) "	"Ulmus americana"
10	"Leaves flecked with white"	"Ulmus minor ‘Variegata’"
10	"Leaves large, very rough above, yellow-green over entire canopy (common) "	"Ulmus glabra ‘Lutescens’"