Annual or perennial herbs, often with arachnose eglandular or glandular hairs. Stems 1–several, erect, usually branched. Leaves entire; basal leaves (when present) sessile, apex acute; cauline leaves alternate, sessile, base amplexicaul, stem-clasping, often decurrent, apex acute. Peduncles elongate with leafy bracts decreasing in size towards the involucres. Inflorescences 1–many per plant. Capitula hemispherical or campanulate, solitary or several loosely clustered together at the end of branches. Involucral bracts free, many-seriate, each with a linear claw-like stereome, or sometimes the lamina of bract at least partially continuous with stereome, unequal, lamina scarious, margins entire. Florets yellow, white or purplish; ray florets female, uniseriate, with a 3–5-toothed, ligule-like limb usually much exceeding the involucres (except in P. arachnoidea); disc florets bisexual, numerous, tubular, deeply 5-lobed. Cypselas terete, minutely papillose; pappus bristles numerous, barbellate to shortly plumose, basally connate or free.
