Jessica's Aster

Symphyotrichum jessicae is known only from the Palouse and Clearwater river drainages of eastern Washington and adjacent northwestern Idaho.

Perennials, 40–150 cm, colonial; long-rhizomatous. Stems 1–5+, as­cending to erect, densely puber­ulent to lanate, especially distally. Leaves thickish, margins entire or shallowly crenate, apices acute to ± obtuse, faces densely lanate-puberulent; basal withering by flowering, petiolate, blades obovate to elliptic, 30–150 × 10–40 mm, bases cuneate to rounded, margins entire, ciliolate, apices acute, faces densely cinereous to lanate; proximalmost cauline sometimes withering by flowering, subpetiolate or sessile, blades obovate-lanceolate to elliptic, 50–100 × 10–25(–35) mm, bases cuneate, clasping, ± auriculate, apices usually acute; distal sessile, blades 20–60(–80) × 9–16(–20) mm, bases rounded to auriculate. Heads in paniculiform, very leafy arrays, branches 4–10(–20) cm. Peduncles densely lanate, bracts 1–8, elliptic, margins ciliolate, apices acute, puberulent. Involucres campanulate, 6–10 mm. Phyllaries in 4–6 series, oblanceolate (outer) to linear (inner), unequal, bases scarious (outer sometimes foliaceous), margins slightly scarious, entire, green zones obovate to elliptic, apices acute, faces densely lanate to cinereous. Ray florets 18–40; corollas violet, laminae (8–)12–20 × 1–2(–2.5) mm. Disc florets 35–80+; corollas yellow, 6–9 mm, lobes triangular, 0.4–1 mm. Cypselae brown, cylindric to obovoid, not compressed, 3.5–4.5 mm, 4–5-nerved, faces sparsely hairy; pappi tawny, (6–)7–9 mm. 2n = 80.

Aster jessicae Piper, Erythea 6: 30. 1898

Symphyotrichum jessicae (formerly Aster jessicae) is a species of flowering plant in the family Asteraceae endemic to Idaho and Washington states in the United States. Commonly known as Jessica's aster, it is a perennial, herbaceous plant that may reach 40 to 150 centimeters (1+1⁄4 to 5 feet) tall. Its flowers have violet ray florets and yellow disk florets. It is of conservation concern and known only from the Palouse River and Clearwater River drainages of eastern Washington and northwestern Idaho.

S. jessicae specimen collected at Nez Perce County, Idaho, 2 September 2004 by Karen L. Gray. Stored at the New York Botanical Garden Steere Herbarium.