Oldfield Hairy White Aster
Symphyotrichum pilosum var. pilosum is very common in southern Ontario and throughout much of the eastern United States. It becomes much less common in southern Québec. Stem height is highly variable depending upon growing conditions. The stems are always hairy (Brouillet et al 2006 FNA). Inflorescences vary from large open pyramidal arrays with many heads to small more racemiform arrays with few heads depending upon growing conditions. Two ploidy levels occur influencing involucre and floret size: tetraploid (2n=32) and hexaploid (2n=48) with the hexaploids confined to glaciated areas. Tetraploids occur through much of the range.
Rarely, pinkish rayed forms occur.
Last revised 15 April 2025 by J.C. Semple
© 2025 J.C. Semple, including all photographs unless otherwise indicated
1-6. Symphyotrichum pilosum var. pilosum. 1. Habitat, limestone bluff, Semple & Chmielewski 5183, Crawford Co, Wisconsin. 2-3. Multiple plants in bloom, Ontario. 4. Large inflorescence, Waterloo R.M., Ontario. 5. Small, hairy stemmed inflorescence, greenhouse grown plant. 6. Flowering head with phyllary tip margins inrolled.