The Manual of the Botany of the Northern United States Part 83

95. Pyrrhopappus. Scapose or branched. Pappus reddish, the base surrounded by a soft villous ring.

96. Chondrilla. Stem branching, leafy. Involucre few-flowered, calyculate. Pappus white.

[+][+] Achenes flat or flattish. Pappus white, fine and soft. Involucre imbricated. Leafy-stemmed, with panicled heads.

97. Lactuca. Achenes more or less beaked. Flowers yellow or purplish.

98. Sonchus. Achenes flattish, not at all beaked. Flowers yellow.

The technical characters of the tribes, taken from the styles, require a magnifying-gla.s.s to make them out, and will not always be clear to the student. The following artificial a.n.a.lysis, founded upon other and more obvious distinctions, will be useful to the beginner.

Artificial Key to the Genera of the Tubuliflorae.

-- 1. Rays or ligulate flowers none; corollas all tubular (or rarely none).

[*] 1. Flowers of the head all perfect and alike.

Pappus composed of bristles:

Double, the outer of very short, the inner of longer bristles No. 2

Simple, the bristles all of the same sort.

Heads few-flowered, themselves aggregated into a compound or dense cl.u.s.ter 1

Heads separate, few-flowered or many-flowered.

Receptacle (when the flowers are pulled off) bristly-hairy 78, 79, 80

Receptacle deeply honeycomb-like 81

Receptacle naked.

Pappus of plumose or bearded stiff bristles. Flowers purple 8

Pappus of very plumose bristles. Flowers whitish 6

Pappus of slender but rather stiff rough bristles 4, 5, 7, 9, 16

Pappus of very soft and weak naked bristles 76, 77

Pappus composed of scales or chaff.

Receptacle naked. Leaves in whorls 3

Receptacle naked. Leaves alternate, dissected 61

Receptacle bearing chaff among the flowers 59, 64

Pappus of 2 or few awns or teeth 53, 57, barbed in 55, 56

Pappus none, or a mere crown-like margin to the fruit 36, 68, 71

[*] 2. Flowers of two kinds in the same head.

Marginal flowers neutral and sterile, either conspicuous or inconspicuous 82

Marginal flowers pistillate and fertile.

Receptacle elongated and bearing broad chaff among the flowers 29, 30

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 dicious; in both kinds many-flowered. Pappus capillary 27, 31, 32, 79

Heads moncious; the fertile 1--2-flowered and closed. Pappus none 43, 44

-- 2. Rays present; i.e. the marginal flowers or some of them with ligulate corollas.

[*] 1. Pappus of capillary bristles, at least in the disk. (Rays all pistillate.)

Rays occupying several rows 26, 72, 73

Rays in one marginal row, and

White, purple or blue, never yellow 17, 24, 25, 26, 73

Yellow, of the same color as the disk.

Pappus (at least in the disk) double, the outer short and minute 13, 14

Pappus simple.

Scales of the involucre equal and all in one row. Leaves alternate 75