A graceful, late-season garden perennial grown for its airy sprays of pink or white saucer-shaped flowers held on tall, wiry stems above a low mound of dark, divided leaves. A horticultural hybrid of East Asian parentage, it blooms from late summer into autumn when most perennials are finished, lighting up part-shaded borders and woodland edges. It wants cool, consistently moist soil and spreads steadily by underground runners, so it rewards a roomy, evenly-watered spot rather than a hot, dry one.