SUNFLOWER FAMILY 
167 
3. A. pycnocephala DC. Stems stout, simple, 4 to 6.5 dm. high; leaves 
once or twice divided into linear lobes; inflorescence a dense virgate 
panicle; involucre villous.—Sand hills along the coast. 
4. A. dracunculoides Pursh. Stems branched, 5.8 to 13 dm. high; 
leaves linear, entire or the lowermost 3-toothed or -cleft; marginal flowers 
fertile, disk-flowers perfect but sterile.—S. Cal., Sierra Nevada, e. and n. 
29. ARNICA L. 
Montane herbs, somewhat glandular or aromatic. Stems single, bear¬ 
ing 1 to several large heads at summit. Leaves mostly opposite. In¬ 
volucre broadly campanulate; bracts somewhat in 2 ranks. Receptacle 
flat, naked. Disk- and ray-flowers yellow. Achenes slender, with a 
callous knob at base. Pappus a single row of strongly roughened white 
bristles. (Origin of name obscure.) 
1. A. discoidea Benth. Coast Arnica. Plants 3.6 to 5.4 dm. high, 
glandular-pubescent above; leaves ovate or oblong, dentate, petioled; 
cauline leaves sessile; rays none.—Dry open woods. 
30. SENECIO L. Groundsel 
Herbs with alternate leaves and heads in terminal corymbs, rarely 
solitary. Heads many-flowered. Disk- and ray-flowers yellow. In¬ 
volucre cylindrical to campanulate. Bracts of equal length in 1 or 2 
rows. Achenes terete. Pappus of abundant white soft hairs. (Latin 
senex, an old man, on account of the white hair-like pappus.) 
Perennials. 
Stems numerously and nearly equably leafy; leaves or their divisions linear 
to filiform.1. S. douglasii. 
Stems few-leaved, naked above or the upper leaves reduced. 
Stems tall and simple, from a coarsely fibrous cluster of roots.. 
2. S’, hydrophilus. 
Stems several or in tufts, from creeping rootstocks.3. Y. aronicoides. 
Annuals; rays none or minute; involucral bracts black-tipped.4. S. vulgaris. 
1. S. douglasii DC. Creek Senecio. Bush 5 to 15 dm. high; herbage 
at first whitish-tomentose, later glabrate; involucre broadly turbinate, the 
bracts linear with attenuate tips; rays about 15.—Dry stream beds or 
moist swales. 
2. S. hydrophilus Nutt. Stem purplish, 6 to 15 dm. high; herbage 
glabrous; leaves fleshy-coriaceous, entire or nearly so; lower leaves short- 
petioled, the upper sessile or partly clasping; heads numerous; rays none 
or rarely few.—Marshes about San Francisco Bay and n. 
3. S. aronicoides DC. Stem robust, 3 to 8.5 dm. high; heads many 
or few; leaves ovate to oblong, the upper auricled at base; rays none, 
rarely 1 or 2.—Thickets or sparsely chaparral-covered country. 
4. S. vulgaris L. Common Groundsel. Stem simple or branching, 
1 to 3 dm. high; leaves pinnatifid with jagged margin; heads in terminal 
corymbs; involucres cylindrical, with conspicuously black-tipped small 
bracts at base.—Common weed from Eur. 
31. CIRSIUM Scop. Thistle 
Stout herbs. Leaves alternate, prickly or spiny-toothed or pinnatifid. 
Head with numerous crimson, white, or yellowish flowers, all tubular. 
Involucre spherical to cylindrical, the bracts imbricated, usually tipped 
