The sweet gum tree creates fireworks in the garden, with star-shape leaves that change to fiery hues in fall. The handsome foliage is glossy green spring through summer. This U.S. native possesses a narrow habit that opens up and rounds with age. A fragrant sap bleeds from the tree when the bark is wounded. Spiny seed balls form on the tree and persist through the winter months. Sweet gum thrives in moist, acidic soil with lots of organic matter.