(formerly Aster mollis) is a species of flowering plant in the aster family (Asteraceae) endemic to the Bighorn Mountains of Montana and Wyoming in the United States. Commonly known as, it is a perennial, herbaceous plant that ranges from 30to in height.
Symphyotrichum molle is a perennial, herbaceous plant which blooms in August. It grows from 30to in height, and it is colonial with long rhizomes in its root system. It has from one to five stems, sometimes more, that are densely covered in soft, downy hairs, sometimes to the extent of being woolly. The stems arise from the root base in an ascending or erect fashion.
The leaves are thin and covered in downy to woolly hairs on both sides. They are smooth around the edges and pointed at the ends. Those at the base are oblanceolate in shape, have short leafstalks (petioles), and are from 1.5to in length and usually 0.5to in width. By the time the plant blooms, the basal leaves usually have withered or dried. The stem leaves (cauline leaves) are longer and wider than the basal leaves, with lengths ranging from 5to and widths from 1to. They may or may not have a petiole, and they are oblanceolate in shape. They slightly clasp the stem. Leaves furthest on the stem (distal leaves), closest to the flowers, are lanceolate rather than oblanceolate, 3– in length, and 1– wide.
The inflorescences of Symphyotrichum molle have flower heads in corymbiform to paniculiform arrays with their branches growing up to 201NaN1 in length. Each head has a hairy peduncle with 0–3 bracts which are either lanceolate to narrowly ovate in shape. The involucres are bell-shaped and in length with oblong to oblanceolate phyllaries that are in 4–5, sometimes up to 6, unequal series.
Its flowers have violet ray florets that are from in length and wide. There are usually yellow disk florets with triangular lobes when they bloom.
Symphyotrichum molle has a base number of eight chromosomes with a tetraploid count of 32.
Symphyotrichum molle is endemic to the Bighorn Mountains of Montana and Wyoming in the United States. It is a montane species that can be found at elevations ranging from 2000to in dry meadows.
NatureServe lists Symphyotrichum molle as Vulnerable (G3) worldwide, Imperiled (S2) in Montana, and Vulnerable (S3) in Wyoming. Its global status was .