Maple Tree Identification: Sugar, Red, Norway

Maples are opposite: leaves and twigs sit in pairs directly across from each other. Virginia Tech's dendrology primer puts maple first in the MAD Cap Horse list of opposite-branched trees, so that one check separates a maple from the oaks, elms, birches and cherries around it.

After that, the species question comes down to a handful of features on a single leaf, plus buds and bark for confirmation. Three species cover most of what people photograph in eastern North America: sugar maple, red maple and the introduced Norway maple.

Collect two or three leaves from different parts of the tree rather than one, because lobe depth varies between sun and shade leaves. If the tree is in a yard, a street planting or a parking lot, weight your guess toward Norway maple and cultivars; if it is in a woodlot, weight it toward the natives.

University of New Hampshire Extension separates these two cleanly, and the difference holds year-round.

• Lobes. Red maple has three lobes, sometimes five if you count the small ones at the base; sugar maple has five.
• Sinuses. The spaces between red maple lobes form sharp V shapes; sugar maple sinuses are U-shaped. UNH offers the memory hook that there is a letter U in sugar.
• Margins. Red maple leaves are finely serrated; sugar maple leaves are smooth along the edges.
• Buds. Red maple buds are bright red, obvious in late winter and spring; sugar maple buds are tan.
• Bark. Young red maple bark is smooth gray, and with age develops narrow vertical plates that peel off easily; sugar maple bark stays very tight to the tree and does not knock off, and carries a small diamond-shaped pattern that UNH admits is hard to see.

UNH adds a seasonal note from syrup production: red maple buds earlier than sugar maple, which is why producers pull taps from red maples first.

Norway maple is the one that trips people up, because its leaf looks like an oversized sugar maple leaf. University of Minnesota Extension gives the test that ends the argument: broken leaves emit milky sap. Snap a leaf or its stalk and watch the break. White, and it is Norway maple; clear, and it is not.

The supporting features from UMN: opposite, five-lobed leaves that are coarsely toothed and pointed, generally wider than tall (sugar maple is generally taller than wide), bark more regularly grooved than sugar maple, and yellow fall foliage.

UMN also explains why this matters beyond naming: Norway maple invades woodlands by out-competing sugar maple thanks to its shade tolerance, forms a dense canopy, and reduces wildflower diversity beneath it. If you are choosing what to plant, that is the reason several states discourage or prohibit it — check your own state's list before buying.

Samaras. Maples carry paired winged seeds — the helicopters. UMN describes Norway maple's as widely spreading winged fruits, noticeably flatter in angle than the narrow V of sugar maple.

Season. Red maple flowers and seeds early in spring, well before most trees leaf out, which is often the first splash of color in a northern woodlot.

Setting. Street trees and parking-lot plantings skew heavily to Norway maple and named cultivars, including the dark-leaved ones sold as purple or crimson forms. A dark red-purple leaf all summer, opposite arrangement, and milky sap in the petiole is a strong combination.

For the app, photograph one leaf laid flat with the stalk showing, the twig so the opposite arrangement is visible, and the trunk at chest height. Photograph it and the app identifies it; the milky-sap check takes two seconds and settles the native-versus-Norway question on your own.