Umbellate aster

Doellingeria umbellata, commonly called parasol whitetop or tall flat-top white aster, is a tall, erect, clump-forming perennial herb in the Asteraceae native to moist meadows, fens, swamp margins, ditches and damp forest openings across eastern and central North America from Quebec and Newfoundland west to Manitoba and south to Georgia and Kentucky. The plant arises from short stout rhizomes and produces one to several unbranched stems 0.5 to 2 metres tall, glabrous below and finely pubescent above. The numerous alternate, sessile or very short-petiolate leaves are lanceolate to elliptic, 5 to 15 centimetres long, sharply tapered at both ends, entire to obscurely toothed, with rough margins and three prominent parallel veins. Flower heads are arranged in a large, distinctly flat-topped, corymbiform terminal panicle 10 to 30 centimetres across; each head is 12 to 20 millimetres in diameter with 5 to 14 narrow white ray florets surrounding numerous yellow disc florets that turn purplish with age, above a campanulate involucre of imbricate green phyllaries. The fruit is a small ribbed achene crowned by a tawny double pappus.