Tonestus peirsonii is a local-endemic species of flowering plant in the family Asteraceae known by the common names Inyo tonestus,[2]Peirson's serpentweed[3] and Peirson's tonestus.
Toiyabea peirsonii is a perennial herb producing a branching stem from a caudex and taproot unit, reaching up to about 20 centimeters tall and taking a clumpy form. The leaves are up to 8 centimeters long, variable in shape but usually broader toward the end, and with toothed edges.[2] Dried remnants of leaves or flowers from previous years may be visible.
The inflorescence is usually a single flower head, or a cluster of up to four heads, each up to 2 centimeters wide with green, rough-haired phyllaries in a broad (14-28mm) somewhat leaf-like involucre below the flower. The head bears 16-20 curling, bright yellow ray florets around a center containing many tubular disc florets. Blooming occurs in July and August.[4]
