Carl Sandburg Home NHS is richly diverse in native flora. A plant inventory performed in 2001 and 2002 uncovered over 520 vascular plant species! Fourteen different vegetation associations (as defined by the United States National Vegetation Classification) lie within the park boundary. From Eastern Emergent Marshes, Cultivated Meadow, Pitch Pine - Table Mountain Pine Woodlands, White Pine - Xeric Oak Forest, Appalachian Shortleaf Pine - Mesic Oak Forest, to Montane Oak - Hickory Forest and the globally rare Appalachian Low-elevation Granitic Dome association, the park is home to numerous species of grasses, ferns, herbs, shrubs, vines, sedges, trees, aquatic plants, mosses and liverworts.
The park is uniquely located between the mountains on the west, and the piedmont on the east, resulting in an interesting variety of terrain, geology and plant communities. Elevations range from 2160 ft near the park entrance to 2783 ft at the summit of Glassy Mountain. On the lower end of the park (north), forest cover is dominated by yellow poplar, white pine, eastern and Carolina hemlock, white and chestnut oak, red maple and sourwood. Mid-elevations are dominated by chestnut oak, northern and southern red oak, white and shortleaf pine, pignut and mockernut hickory, sourwood, black gum and Fraser magnolia. Higher elevations support scarlet and red oaks; shortleaf, white and pitch pine; pignut and sand hickory; red maple, black gum and sourwood. Forest understory throughout the park is dominated by heath species including rhododendron, mountain laurel, azalea, and several species of blueberry and huckleberry. There are at least 56 tree species occurring within the small, 264-acre park.