Culture
Easily grown in average, medium moisture, well-drained soils in full sun. Intolerant of shade. Prefers deep, moist, fertile soils, but seems to tolerate a wide variety of soils. Avoid alkaline soils. Trees are not reliably winter hardy in the northern areas of USDA Zone 5.
Noteworthy Characteristics
Liquidambar styraciflua, commonly called sweet gum, is a low-maintenance deciduous shade tree that is native from Connecticut to Florida and Missouri further south to Texas, Mexico and Central America. In Missouri, it typically occurs in moist low woods and along streams only in the far southeastern corner of the state (Steyermark). It typically grows to 60-80’ (less frequently to 120’) tall with a straight trunk. Habit is pyramidal in youth, but it gradually develops an oval-rounded crown as it matures. Glossy, long-stalked, deep green leaves (4-7” across) have toothed margins. Each leaf has 5-7 pointed, star-shaped lobes. Leaves are fragrant when bruised. Fall color at its best is a brilliant mixture of yellows, oranges, purples and reds. Branchlets may have distinctive corky ridges. Non-showy, monoecious, yellow-green flowers appear in spherical clusters in April-May. Female flowers give way to the infamous gum balls which are hard, spherical, bristly fruiting clusters to 1.5” diameter. Gum balls mature to dark brown and usually remain on the tree through the winter, but can create clean-up problems during the general period of December through April as the clusters fall to the ground. In pedestrian areas, fruiting clusters must be cleaned up because they not only create unsightly litter, but also create human safety problems (e.g., turning an ankle by inadvertently stepping on a cluster). Tree wood has been widely used for a number of applications including flooring, furniture and home interiors. The gum obtained from genus plants has been used in the past for a variety of purposes, including chewing gum, incense, perfumes, folk medicines and flavorings.
Genus name comes from the Latin words liquidus meaning liquid and ambar meaning amber as two species produce a fragrant resin.
Specific epithet means flowing storax.
The common name of sweet gum refers to an aromatic balsam or gum that exudes from wounds to the tree.
'Rotundiloba' is a narrowly pyramidal, deciduous tree which typically grows 60-75' tall (less frequently to 100'). Deep green leaves have, as the cultivar name suggests, distinctively rounded lobes (5-7). Foliage turns yellow to burgundy in fall. Non-showy, apetalous, monoecious flowers appear in small clusters in spring. Tree does not set fruit (the infamous gum balls).
Problems
No serious insect or disease problems. Webworms, caterpillars, borers and scale may cause problems in some areas. Leaf spots, wood rot and bleeding necrosis may occur. Chlorosis may occur in alkaline soils.
