Flora of North America species comparison

erect, branched.

cauline; mostly alternate (proximal 2–6 sometimes opposite);

petiolate;

blades lanceolate, linear, ovate, rounded-deltate, or suborbiculate, often ± palmately or pinnately lobed, ultimate margins entire or ± toothed, faces hirtellous or ± strigose, usually gland-dotted as well.

involucres ± saucer-shaped, 3–5 mm diam.;

phyllaries 6–16+ in 1–2+ series, distinct to bases;

receptacles conic to columnar;

paleae spatulate to cuneiform or linear, membranous, distally ± villous or hirtellous;

florets 20–50+, corollas whitish, ± funnelform, lobes 5, erect or reflexed (filaments connate, anthers distinct or weakly coherent).

involucres ± ellipsoid, 2–5+ mm diam. at anthesis (6–20+ mm diam. at maturity);

phyllaries 30–75+ in 6–12+ series, outer 5–8 distinct, the rest (sometimes interpreted as paleae) proximally connate, their distinct tips mostly ± hooked (the distal 1–3 usually longer, stouter, and not hooked), the whole becoming a hard, prickly perigynium (a bur);

florets 2, corollas 0.

discoid, either pistillate (proximal) or functionally staminate (distal), in racemiform to spiciform arrays or borne singly (in axils).

(black) ± fusiform, enclosed in obovoid to ellipsoid, hard, prickly, 2-chambered burs;

pappi 0.

= 18.