CIOHORIACEAE. 



381 



4. SONCHUS [Tourn.] L. 



Succulent herbs, with alternate, mostly clasping, spinulose-margined leaves, 

 and peduncled, corymbose or paniculate heads of yellow flowers. Involucre 

 ovoid or campanulate, usually becoming thickened at the base when old, its 

 bracts imbricated in several series. Receptacle flat, naked. Anthers sagittate. 

 Achenes oval to linear, 10-20-ribbed, narrowed, truncate. Pappus of very 

 copious soft white simple capillary bristles. [Greek name of the Sow-thistle.] 

 About 45 species, of the Old World. Type species: Sonchus oleraceus L. 



Auricles of the leaves acute; achenes striate, transversely wrinkled. 1. S. oleraceus. 

 Auricles rounded ; achenes ribbed, not transversely wrinkled. 2. S. asper. 



1. Sonchus oleraceus L. 



Annual Sow-Thistle. Hare's 

 Lettuce. (Fig. 413.) Annual; 

 stem leafy below, l°-6° high. 

 Basal and lower leaves petioled, 

 lyrate-pinnatifid, 4-10' long, 

 the terminal segment commonly 

 large and triangular, the mar- 

 gins denticulate with mucronate 

 teeth; upper leaves pinnatifid, 

 clasping by an auricled base, 

 the auricles pointed ; uppermost 

 leaves often lanceolate and en- 

 tire; heads pale yellow, about 

 V broad; achenes striate and 

 wrinkled. 



Common in waste and culti- 

 vated grounds. Naturalized. Na- 

 tive of Europe. Widely natural- 

 ized in temperate and tropical 

 regions. Spring to autumn. 



2. Sonchus asper (L.) All. 

 Spiny or Sharp-fringed Sow- 

 Thistle. (Fig. 414.) Annual, 

 similar to the preceding species; 

 leaves undivided, lobed or some- 

 times pinnatifid, spinulose-dentate 

 to spinulose-denticulate, the lower 

 and basal ones obovate or spatu- 

 late, petioled, the upper oblong or 

 lanceolate, clasping by an auricled 

 base, the auricles rounded; heads 

 several or numerous, 1' broad or 

 less; flowers pale yellow; achenes 

 ribbed. [S. oleraceus asper L.] 



Occasional in waste and cultivated 

 grounds. Naturalized. Native of 

 Europe. Widely naturalized in North 

 America. Flowers from spring to 

 autumn. 



