SUNFLOWER FAMILY 
169 
34. CENTAUREA L. Star Thistle 
Rigid herbs with alternate leaves which are not prickly. Involucre 
ovoid or globose, the bracts imbricated and ending in a needle-like prickle. 
Receptacle with dense persistent bristles. Flowers yellow or purple, all 
tubular. Pappus of 2 or 3 rows of bristles or short scales. (Named for 
one of the Centaurs who used it in healing.) 
Flowers yellow ; leaves decurrent on the stem. 
Annual; plants erect, branching mostly above the base.1. C. melitensis. 
Perennial; plants diffuse, branching from the base.2. C. solstitialis. 
Flowers purple or blue; leaves not decurrent.3. C. calcitrapa. 
1. C. melitensis L. Napa Thistle. Erect branching annual, 3 to 6 
dm. high, the stem winged by the decurrent leaves; lowest leaves pin- 
natifkl, the upper mostly entire; flowers yellow; pappus-bristles in about 
3 rows.—-Common weed of agricultural lands, nat. from Eur. 
2. C. solstitialis L. Yellow Star Thistle. Diffuse, branching from 
the base, 3 to 7 dm. high, cottony pubescent; basal leaves pinnatifid, can- 
line linear, decurrent; flowers bright yellow.—Nat. from Eur., a highly 
noxious thistle of cultivated field and open lands, causing great loss to 
agricultural interests. When botanists first made known its presence in 
California it could have been exterminated for less than a hundred dol¬ 
lars ; at the present time millions of dollars would not suffice. 
3. C. calcitrapa L. Purple Star Thistle. Dense bushy plants 7 
to 11 dm. high; leaves pinnately divided or the uppermost undivided; 
flowers purple; achenes without pappus.—Nat. from Eur.; a highly offen¬ 
sive alien, making taller and denser spiny thickets of growth than no. 2, 
but keeping mostly to uncultivated land. Its presence as a dangerous 
weed was made known by botanists in 1885. 
35. HYPOCHAERIS L. 
Herbs with naked stems bearing a solitary head or a somewhat corym¬ 
bose cluster of long-peduncled heads. Flowers yellow. Leaves in a 
basal rosette. Involucre campanulate or cylindrical, its bracts rather 
few, lanceolate, imbricated. Achenes 10-ribbed, narrowly oblong, taper¬ 
ing into a slender beak. Pappus of plumose bristles. (Greek name used 
by Theophrastus for some cichoriaceous plant.) 
1. H. glabra L. Smooth Cat's-ear. Stems several, erect, mostly 
corymbosely branched, 1.4 to 3.8 dm. high; leaves broadest above; heads 
campanulate.—Cult, fields and pasture lands, a widely spread weed; 
nat. from Eur. 
36. PICRI3 L. 
Coarse rough-bristly biennial with leafy stems. Heads terminal or 
along the branches. Flowers yellow. Outer bracts of involucre loose 
and spreading, inner bracts erect. Achene somewhat flattened, with a 
long beak. Pappus of densely plumose bristles. (Greek pikros, bitter.) 
1. P. echiodes L. Bristly Ox-tongue. Stems branching, 2.8 to 8.6 
dm. high, hispid with barbed hairs; leaves narrowly oblong, sessile, 
rough-hispid.—Open fields and waste grounds, an offensive weed; nat. 
from Eur. 
