Lyall's Goldenweed

Tonestus lyallii is widespread in the central Rocky Mountains and ranges of the Pacific Northwest, and is known in the Great Basin from collections in the Ruby Mountains in Elko County, Nevada. Populations documented from the Coast Range in Siskyou and Trinity counties, California, are disjunct from those in Oregon and Washington by more than 700 km.

Perennials, loosely cespitose, 4–8.5(–15) cm; with branched caudices surmounting poorly developed taproots, or short rhizomes. Stems glabrous , densely stipitate-glandular. Leaves: basal blades linear to spatulate, 30–85 × 3–12 mm; cauline blades oblong to broadly lanceolate, 12–37 × 3–9(–12) mm, gradually reduced distally; 3–5-nerved, margins entire, eciliate, stipi-tate-glandular, faces stipitate-glandular . Peduncles 2–5 mm . Heads 1(–2). Involucres broadly campanulate, 11–22 × 8–11 mm. Phyllaries 18–42, in 3–4(–5) series, , 1- or weakly 3-nerved, ± equal, margins eciliate; outer and mid oblong to broadly lanceolate, 5.2–9.5 × 1–3.5 mm, stipitate-glandular, apices acute; inner green or anthocyanic, linear, 8–13 × 1–2 mm, chartaceous proximally, margins scarious, fimbriate and/or stipitate-glandular distally , apices acute to acuminate, sometimes reflexed, faces stipitate-glandular distally. Ray florets 11–23; laminae elliptic, 6.5–8 × 1–3.5 mm. Disc florets 27–56; corollas narrowly funnelform, 5.5–8.5 mm, scarcely exceeding involucres, lobes erect to spreading, 0.6–0.8 mm, lengths ¹ / 10 – ¹ / 5 corollas; anthers 2–2.5 mm; style-branch appendages lanceolate, 0.7–1 × 0.2–0.3 mm, stigmatic lines 0.9–1.4 mm. Cypselae linear, 2.5–5.5 mm, 8–12-nerved, faces glabrous or sparsely hairy distally; pappus bristles 35–52, flexible. 2n = 18.

Haplopappus lyallii A. Gray, Proc. Acad. Nat. Sci. Philadelphia 15: 64. 1864 (as Aplopappus lyalli)

Tonestus lyallii is a species of flowering plant in the family Asteraceae known by the common names Lyall's goldenweed, Lyall's serpentweed and Lyall's tonestus. It is native to western North America, particularly in the Rocky Mountains and the mountain ranges of the Pacific Northwest with scattered occurrences between. It is a perennial herb growing in clumps or short bunches not more than about 15 centimeters tall, the stem branching from a tough caudex. The leaves are smooth-edged and linear or lance-shaped, the largest at the base of the plant reaching up to about 8 centimeters long. The inflorescence is a single flower head or a pair of heads each about a centimeter wide with green or red phyllaries. The head bears at least 10 or 11 bright yellow ray florets around a center containing many tubular disc florets.

Tonestus lyallii là một loài thực vật có hoa trong họ Cúc. Loài này được (A.Gray) A.Nelson miêu tả khoa học đầu tiên năm 1904.