Leaf shapes and characteristics of five common types of trees
In human families, the members often resemble each other. Trees are much the same. When you learn the general appearance of one tree's leaf, you can often recognize its relatives. You can say, "That leaf looks like a willow," just as you might say, "That boy looks like a Johnson."
And keep in mind that there are always exceptions -- some leaves don't look exactly like their relatives in every detail.
Here are some generalizations that will help you recognize five common tree families:
MaplesLong-stalked, toothed, broad leaves, shaped somewhat like a hand with the fingers spread ("palmate lobes").
Right: Red maple
WillowsLong, slender leaves, arranged alternately on long thin branches. The trees are usually found in wet areas.
PoplarsBroad, shiny leaves with a heart shape, toothed edge, and bright green color. Long slender stems allow the leaves to dance in a breeze.
Image credit for Plains cottonwood: USDA-NRCS PLANTS Database / Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. Vol. 1: 591.