Receptacle convex, chaffy. Achene flat, 2-awned 52
Receptacle naked or bearing no conspicuous chaff.
Pappus of capillary bristles. Involucre imbricated 28, 32, 33
Pappus of capillary bristles. Involucre merely one row of scales 26, 73, 77
Pappus a short crown or none.
Achenes becoming much longer than the involucre 34
Achenes not exceeding the involucre 42, 70, 71
[*] 3. Flowers of two kinds in separate heads, the one pistillate, the other staminate.
Heads diœcious; in both kinds many-flowered. Pappus capillary 27, 31, 32, 79
Heads monœcious; the fertile 1–2-flowered and closed. Pappus none 43, 44