Spring Flora of Oklahoma 
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lobes of the calyx or none. Stamens 4-12, hypogynous. 
Ovary 2-celled. Styles 2. Fruit a double key. 
I. ACER (Tourn.) L. 
Characters of the genus the same as for the family. 
Leaves simple, palmately lobed. 
Flowers in dense, sessile, lateral clusters, unfolding 
before the leaves. 
Petals none; ovary tomentose, samaras divergent. 
1. A. saccharinum. 
Petals present; ovary glabrous, samaras incurved. 
2. A. rubrum. 
Flowers corymbose, lateral, unfolding with the 
leaves. 
Leaves pale and nearly glabrous beneath. 
3. A. saccharum. 
Leaves green and pubescent, at least on the veins, 
beneath. 4. A. nigrum. 
Leaves pinnate. 5. A. Negundo. 
1. Acer sacchharinum L. Silver Maple. A large tree. Leaves 
4'-6' long, deeply 5-lobed, coarsely and irregularly dentate, green 
above, silvery white beneath. Flowers greenish to red, in corymbs. 
Stamens 3-6. Samaras pubescent, divaricate. 
Along streams. February-April. Cultivated. 
2. Acer rubrum L. Scarlet Maple. Large tree. Twigs reddish. 
Leaves sharply 3-5-lobed, the lobes irregularly dentate. Flowers 
red or yellowish in sessile lateral clusters. Stamens 3-6. Samaras 
glabrous, slightly incurved. 
In swamps and low grounds. March-April. Eastern and central 
part of the state. 
3. Acer saccharum Marsh. Sugar Maple. A large tree. Leaves 
3'-6' long, 3-7-lobed, the lobes acuminate, irregularly sinuate, the 
sinuses rounded. Flowers greenish-yellow, in lateral or terminal 
corymbs, drooping on capillary hairy pedicels, appearing with the 
leaves. Petals none. Samaras glabrous, slightly diverging. 
In rich woods. April-May. Southeastern part of the state. 
4. Acer nigrum Michx. Black Sugar Maple. A large tree with 
rough, blackish bark. Leaves similar to preceding, but lobes much 
