Symphyotrichum potosinum

The leaves are thin and grass-like, hairless or nearly so. Those at the base have long, sheathing, and sparsely ciliate petioles, and they are from 4 to 11 centimeters (1.6 to 4.3 inches) in length and usually 5–7 mm in width. By the time the plant flowers, the basal leaves are usually withered, yet the stem leaves usually remain. The leaves along the stem range in length from 5 to 12 cm (2 to 5 in) and sometimes up to 18 cm (7 in). They are also grass-like, and typically not as wide as those at the base, with width measurements from 1–6 mm. The leaves highest on the stem are either grass-like or awl-shaped with a tapering point, shorter from 1 to 5 cm (0.4 to 2.0 in), and very thin at only 1–2 mm wide.[3]

S. potosinum flower heads, pressed and dried

The inflorescences of Symphyotrichum potosinum consist of a usual range of 3 to 20 flower heads in paniculiform arrays with their branches growing at 45–50° angles to the stem. Each head has a 1–4 cm (0.4–1.6 in) hairless peduncle with 1–4 bracts. The involucres are cylindric to hemispheric in shape and 5–7.3 mm in length. The phyllaries are in 2–3, sometimes up to 5, series, and awl-shaped to lanceolate.[3]

Its flowers have 14–27 white ray florets that are from 4.6 to 10.3 mm in length and 1.3–2 mm wide. There are usually 18–35 yellow disk florets with triangular spreading lobes when they bloom.[3]

S. potosinum specimen stored at Deaver Herbarium, Northern Arizona University. Collected 11 June 2016, Garden Canyon, Fort Huachuca, Huachuca Mountains, Cochise County, Arizona, at 1,844 m (6,050 ft).

Symphyotrichum potosinum has a base number of five chromosomes (x = 5)[5] with a diploid count of 10.[3]