Observation of Sugar maple group
Reference Books are as follows ;
"An Illustrated guide of Maples" by ANTONIE LE HARDY DE BEAULIUU
"Maples of the world" by D.M.van Geideren
Besides the standard type of sugar maple (Acer saccharum), black sugar maple (Acer nigrum), chalk maple (Acer leucoderme), Florida sugar maple (Acer floridanum) and canyon maple (Acer grandidentatum) are well-known as "sugar maples group" .
I tried to observe these 3 types of young seedlings of 5-10 years, such as the standard of sugar maple, black sugar maple and chalk maple refering the upper terms.
At first, let me show you the figure of 3 types.
Chalk maple at left, sugar maples at front center & right, black sugar maple at center back
Secondly, on leaves figures
upper : sugar maple, middle : black sugar maple, lower : chalk maple
Thirdly, on the upper side of leaves
The upper two : sugar maples, light green at left, dark green at right
Lower : dark green of black sugar maple at left, green of chalk maple at right
We can find that apices are sharply acute & that lobes has many teeth in leaves of sugar maple. And we can find that margins are irregularly toothed, lobes are not well defined & that apices are acute in black maple. We can also find that lobes are almost triangular & that the petiole is red in chalk maple.
Lastly, let's observe the underside of leaves.
Upper row : sugar maple, glabrous but pubescent only at the axils of the major veins
Middle row : black sugar maple, with a thick velvety down extending to the petiole
Lower row : chalk maple, with velvety down on all leaves below except petiole