Granite Serpentweed

Tonestus graniticus is known only from the Great Basin, from the east side of Lone Mountain, Esmeralda County.

Perennials, cespitose to ± mat-forming, 5.5–14 cm; with branched caudices surmounting well-developed taproots. Stems (clothed with marcescent leaf bases) densely stipitate-glandular. Leaves: basal blades ovate to spatulate, 12–40 × 5–12 mm; cauline petiolate (proximal) to sessile and ± clasping (distal), blades oblong to broadly lanceolate, 4–28 × 1–8 mm, markedly reduced distally; 1- or very weakly 3-nerved, margins usually irregularly den­tate, rarely (basal, distal) entire, faces densely scabrous (hairs multicellular, conic), stipitate-glandular. Heads (1–)3–7(–11), in racemiform or apparently corymbi-form arrays. Peduncles 0–15 mm (often apparently bracteolate). Involucres narrowly campanulate, 5–9 × 6–10 mm. Phyllaries 18–32, in 3–4 series, often reflexed distally, green, 1-nerved, unequal, proximally chartaceous and ± keeled, margins eciliate, faces stipitate-glandular; outer and mid ovate to oblong, 2–6 × 1–2 mm, apices obtuse to acute; inner linear to narrowly lanceolate, 4–6 × 1–2 mm, margins scarious, stipitate-glandular distally, apices acute to acuminate. Ray florets 0. Disc florets 13–23; corollas funnelform to ± ampliate distally, 3.5–5.5 mm, scarcely exceeding involucres, lobes erect to slightly spreading, 0.8–1 mm, ¹ / 5 – ¹ / 4 corolla length; anthers 1.6–2.1 mm; style-branch appendages lanceolate, 0.7–1.1 mm, stigmatic lines 0.6–1.1 mm. Cypselae cylindric, 1.5–3 mm, weakly 4–7-nerved, faces strigose; pappus bristles 25–35, brittle. 2n = 18.

Haplopappus graniticus Tiehm & L. M. Schultz, Brittonia 37: 165, fig. 1. 1985

Tonestus graniticus, common names granite serpentweed and Lone Mountain serpentweed, is a rare endemic plant species known only from the east side of Lone Mountain in Esmeralda County, Nevada, about 20 km (12.5 miles) west of Tonopah. It grows there in the crevices of granitic outcrops.

Tonestus graniticus is a perennial herb growing close to the ground and forming mats. Leaves are ovate to spatulate, irregularly toothed, up to 4 cm (1.6 inches) long. Flower heads are born in racemose or corymbiform arrays. There are no ray flowers, but up to 23 yellow disc flowers.