Michaelmas daisy

Symphyotrichum pilosum, known as hairy white oldfield aster or frost aster, is a perennial herb of the family Asteraceae native to central and eastern North America. From a branched, woody caudex with short rhizomes it sends up one to several straight, leafy stems typically 30-120 cm tall, often clothed in spreading hairs in the typical variety. The thin, alternate leaves are oblanceolate to linear, the basal ones 1-6 cm long and the stem leaves becoming narrower and shorter upwards. From late summer through autumn the plant produces airy panicles of numerous small flower heads, each 13-19 mm wide with 16-28 white ray florets surrounding a central disc of yellow florets that age to reddish-purple. It is a common pioneer of old fields, roadsides, and prairies and has become naturalised in parts of Europe.