Flora of North America species comparison

mostly cauline, sometimes basal or basal and cauline; mostly opposite (distal sometimes alternate) or mostly alternate; petiolate or sessile;

blades usually elliptic, filiform, lanceolate, linear, or ovate, often 1(–2)-pinnately lobed, ultimate margins entire or toothed (often proximally bristly-ciliate), faces glabrous or puberulent to tomentose (usually bearing oil-glands, embedded pellucid glands filled with strong-scented, essential oils).

campanulate, cylindric, hemispheric, obconic, or turbinate.

flat or convex to hemispheric or conic, epaleate (receptacles sometimes pitted, pit margins sometimes fimbrillate to laciniate).

0 or 1–21+, pistillate, fertile;

corollas yellow to orange (sometimes with brown or mostly brown) or white to pink, magenta, or reddish purple.

1–120+, usually bisexual and fertile [functionally staminate];

corollas yellow to orange or brown, or pinkish to purplish or reddish, tubes much shorter than to much longer than cylindric to funnelform throats, lobes 5, deltate to lance-linear (equal or unequal);

anther thecae pale or ± darkened;

stigmatic papillae in 2 lines.

falling or persistent, 3–21+ in 1–2 series (distinct or ± connate, mostly linear to lanceolate, usually subequal, usually some or all bearing pellucid oil-glands as in leaves).

0 or of 1–22 bractlets.

radiate or discoid (sometimes radiant, e.g., in Thymophylla), usually borne singly, sometimes in loose to crowded, corymbiform or cymiform arrays.

mostly clavate to obpyramidal (lengths usually 2–3+ times diams.), glabrous or hairy;

pappi usually persistent, of 20–50 bristles in 1–2+ series, or of 5–20 (sometimes aristate) scales in 1–2 series, or combinations of bristles and scales in 1–2+ series, rarely coroniform or 0.