Symphyotrichum undulatum aka Clasping Heart Leaf Aster

Symphyotrichum undulatum, or wavy leaf aster, is a perennial herb. It belongs to the aster family, Asteraceae. It is native to central and eastern North America. Its range includes eastern Canada and much of the eastern United States. It grows in open woods, clearings, and by roads. It also grows on sandhills, in dry hammocks, and on wooded bluffs. The name undulatum refers to its wavy leaves.

Plants form clumps about 1–2 feet [0.30–0.61 metres] wide. Stems tend to reach 1–4 feet [0.30–1.22 metres] tall. NCSU also lists heights reaching 5.2 feet [1.57 metres]. The green stems grow upright and branch but break with ease. Some have smooth surfaces; others have a thick coat of fine hairs. Rough leaves grow in turn along the stem, not in pairs. They range from oval to lance-shaped. Lower leaves have winged stalks. Upper leaves clasp the stem. Leaf edges may have shallow teeth or be almost smooth. Leaves at the base wither after bloom. At times, a rosette, or ring of leaves, forms in winter.

Loose groups of daisy-like flower heads open in fall. Each stem in bloom bears at least four heads. The outer ray flowers are lavender or blue. The small disk flowers have a tube shape and more colors. These may be yellow, white, pink, red, purple, or blue. Heavy groups of blooms can make taller stems lean. After bloom, the plant forms small fruits called achenes. These turn tan, pale brown, or dull purple. They have thin bristles and tufts of pale or pink-tinged hair. Fruits can stay on the plant into winter.

This aster does best in part shade or light through trees. It also copes with full sun and dry, rocky sites. It can grow in loam, sand, and shallow, rocky soil. It likes soil that drains well, with an acidic to neutral pH. NCSU lists it for USDA zones 3a through 8b. It grows fast and needs little care. Trim in summer to curb height if stems grow too tall. Grow new plants from seed or split clumps once established. Plants also spread by seed and rhizomes, which are underground stems.

Use it in woodland gardens, borders, or areas left to grow wild. Groups of plants can suit rocky slopes and other tough sites. Its late blooms give insects pollen and nectar. Bees and butterflies visit. Several kinds of caterpillars feed on it and may harm leaves. Deer browse plants at times. NCSU reports no major pest or disease concerns as a whole. Its page also names southern blight as a possible problem.