People often are of two minds when it comes to sweet gums: They praise them for their ravishing fall color but curse them for their copious gum balls. Distinguished by their maplelike leaves, they're upright, conical trees that spread with age. Inconspicuous flowers are followed by spiny seed balls that are a boon for fans of dried arrangements but a bane for those who like to walk barefoot. Seedless selections are becoming available, however, so the best of both worlds could be in sight.
Provide fertile, well-drained, slightly acid to neutral soil; alkaline soil often causes chlorosis (yellow leaves with green veins), and the problem can be hard to correct. Prune young trees to develop a strong central leader. Mature trees need little pruning.
Given ample room, sweet gums make fine street and shade trees, though their surface roots can be a problem in lawns or in the narrow space between sidewalk and curb. Fall foliage is brilliant in the Upper and Middle South, less so in the Lower, Coastal, and Tropical South. Young plants are somewhat resistant to browsing deer.
L. formosana. CHINESE SWEET GUM. Zones US, MS, LS, CS; USDA 6-9. Native to China. To 4060 ft. tall, 25 ft. wide. Free-form outline; sometimes pyramidal, especially when young. Three- to five-lobed leaves are 34 in. across, violet-red when expanding, deep green at maturity. Fall color ranges from red in northern part of range to yellow-beige farther south. Leaves drop late, usually in early winter. 'Afterglow' has lavender-purple new growth, rosy red fall color.
L. orientalis. ORIENTAL SWEET GUM. Zones MS, LS, CS; USDA 7-9. Native to Turkey. To 2030 ft. tall and wide. Leaves 23 in. wide, deeply five lobed, each lobe again lobed to give a lacy effect. Leafs out early after short dormant period. Fall color varies from deep gold and bright red in cooler areas to dull brown-purple farther south.
L. styraciflua. AMERICAN SWEET GUM. Zones US, MS, LS, CS; USDA 6-9. Native to eastern U.S., and by far the most commonly planted sweet gum. To about 60 ft. tall in gardens; much taller in the wild. Narrow and erect in youth, with lower limbs eventually spreading to 2025 ft. Tolerates damp soil. Good-looking all year. Branching pattern, furrowed bark, and corky wings on twigs all provide winter interest, as do hanging seedpods-in., spiky spheres reminiscent of tiny medieval maces. On mature trees, seedpods are profuse enough to cause a litter problem (especially on lawns, where they interfere with mowing).
Five- to seven-lobed, 3- to 7-in.-wide leaves are deep green in spring and summer, turning to purple, yellow, or red in fall. Seedling trees usually give good fall color, though color varies widely. To get desired and uniform color, purchase named selections, preferably while they are in fall color. Good selections include the following.
'Burgundy'. Deep purple-red fall color. Foliage hangs on late into winteror even into early spring if storms are not heavy.
'Cherokee'. Produces very few or no seedpods. Fall color is burgundy-red (yellow on trees grown in shade).
'Festival'. Narrow, columnar. Light green foliage turns a combination of yellow, peach, pink, orange, and red in fall.
'Golden Treasure'. Deep green leaves bordered in gold. In fall, gold rim lightens to pale yellow, then white; green center turns burgundy.
'Gumball'. Dense, rounded, shrubby habit rarely over 6 ft. on its own. When grafted as a standard tree, forms a neat round-topped tree, 1012 ft. high and wide. Burgundy-red in fall.
'Palo Alto'. Orange-red to bright red fall color.
'Rotundiloba'. Leaves have rounded rather than sharp-pointed lobes. Sets no seedpods. Fall color is yellow, red, burgundy, and purple. Weak-wooded and subject to storm damage.
'Silver King'. Leaves are edged in creamy white; may be flushed with rosy tones in late summer and fall.
'Slender Silhouette'. Grows 60 ft. tall, 8 ft. wide; orange to burgundy fall color.
'Variegata'. Green leaves with yellow streaks and splotches. In fall, the yellow variegation turns pink; green part of leaf becomes red.