ACERACEAE, the Maple Family
Trees or shrubs, with opposite, lobed or compound leaves and inconspicuous flowers; sepals about 5; petals the same number, or none; stamens 4-12; ovary 2-lobed, ripening into a pair of winged fruits.
| 1a. Leaves compound (tree; flowers appearing before the leaves) | Box Elder, Acer negundo. |
| 1b. Leaves simple (Maple) [— 2.] | |
| 2a. Shrubs or small trees; leaves 3-5-lobed; the lobes with regularly serrate margins (flowers greenish-yellow, appearing later than the leaves) [— 3.] | |
| 2b. Trees; leaves 3-7-lobed; margins of the lobes entire or incised, but never regularly serrate [— 4.] | |
| 3a. Leaves finely and sharply serrate; twigs smooth; bark conspicuously striped with white lines | Striped Maple, Acer pennsylvanicum. |
| 3b. Leaves coarsely and bluntly serrate; young twigs pubescent; bark not striped | Mountain Maple, Acer spicatum. |
| 4a. Angles between the leaf-lobes rounded (flowers greenish-yellow, appearing with the leaves) [— 5.] | |
| 4b. Angles between the leaf-lobes acute or obtuse, but not rounded (flowers purple, red, or yellowish, appearing before the leaves) [— 6.] | |
| 5a. Leaves glabrous beneath, or minutely pubescent on the veins | Sugar Maple, Acer saccharum. |
| 5b. Leaves downy beneath | Black Maple, Acer saccharum var. nigrum. |
| 6a. Middle leaf-lobe usually more than half the length of the leaf, narrowed at its base; broken twigs with a strong odor | Silver Maple, Acer saccharinum. |
| 6b. Middle leaf-lobe usually less than half the length of the leaf, its sides parallel or broadened at the base; broken twigs without strong odor | Red Maple, Acer rubrum. |
SAPINDACEAE, the Soapberry Family
Trees, with opposite palmately compound leaves, and showy white or yellowish flowers in panicles in spring; sepals 5; petals 4 or 5; stamens about 7; fruit a smooth brown nut.
| 1a. Leaflets 7; buds viscid; corolla of 5 petals | Horse Chestnut, Aesculus hippocastanum. |
| 1b. Leaflets 5; buds smooth; corolla of 4 petals | Buckeye, Aesculus glabra. |
BALSAMINACEAE, the Touch-me-not Family
Smooth herbs, with alternate simple leaves and showy flowers; one petal-like sepal prolonged into a spur; fruit explosive when ripe (5-10 dm. high; summer).