GENUS 16. 



CHICORY FAMILY. 



3*7 



2. Sonchus oleraceus L. Annual Sow- 

 Thistle. Hare's Lettuce. Fig. 4066. 



Sonchus oleraceus L. Sp. PI. 794. 1753. 



Annual, with fibrous roots ; stem leafy be- 

 low, nearly simple, i-io high. Basal and 

 lower leaves petioled, lyrate-pinnatifid, 4'-io' 

 long, the terminal segment commonly large 

 and triangular, the margins denticulate with 

 mucronate or scarcely spiny teeth ; upper leaves 

 pinnatifid, clasping by an auricled or sagittate 

 base, the auricles acute or acuminate; upper- 

 most leaves often lanceolate and entire; heads 

 several or numerous, pale yellow, 9"-is" 

 broad ; involucre glabrous, 6"-8" high ; achenes 

 flat, longitudinally ribbed and transversely 

 rugose. 



In fields and waste places, a common weed in 

 most cultivated parts of the globe except the ex- 

 treme north. Also in Central and South America. 

 Naturalized from Europe. Hare's-colewort or 

 -thistle. Milk-weed. Milk-thistle. Milky tassel. 

 Swinies. The leaves used as a salad and as a pot herb. 



May Nov. 



3. Sonchus asper (L.) Hill. Spiny or Sharp- 

 fringed Sow-Thistle. Fig. 4067. 



Sonchus oleraceus var. asper L. Sp. PI. 794. 1753. 

 Sonchus asper Hill, Herb. Brit. 47. 1769. 



Annual, similar to the preceding species; leaves 

 undivided, lobed or sometimes pinnatifid, spinulose- 

 dentate to spinulose-denticulate, the lower and basal 

 ones obovate or spatulate, petioled, the upper oblong 

 or lanceolate, clasping by an auricled base, the 

 auricles rounded; heads several or numerous, i' 

 broad or less ; flowers pale yellow ; involucre gla- 

 brous, about 6" high; achenes flat, longitudinally 

 ribbed. 



In waste places throughout most of our area and in 

 tropical and South America. Widely distributed as a 

 weed in nearly all cultivated parts of the earth. Nat- 

 uralized from Europe. May-Nov. 



17. LACTUCA [Tourn.] L. Sp. PI. 795. 1753. 



Tall leafy herbs, with small panicled heads of yellow, white, pink, or blue flowers, and 

 alternate leaves. Involucre cylindric, its bracts imbricated in several series, the outer shorter, 

 or of I or 2 series of principal nearly equal inner bracts, and several rows of short outer ones. 

 Receptacle flat, naked. Rays truncate and 5-toothed at the summit. Anthers sagittate at 

 the base. Style-branches mostly slender. Achenes oval, oblong or linear, flat, 3~5-ribbed 

 on each face, narrowed above or tipped by a filiform beak, which is somewhat expanded 

 at the summit into a small disk bearing the copious soft capillary white or brown pappus- 

 bristles. [The Ancient Latin name, from lac, milk, referring to the milky juice.] 



About 100 species, natives of the northern hemisphere. Type species: Lactuca sativa L. 



A. Achenes filiform-beaked; rays mainly yellow. 

 Introduced European species ; heads few-flowered. 



Panicle widely branching ; achene about as long as its beak. 

 Panicle-branches nearly erect ; achene shorter than its beak. 

 Native species ; heads several- to many-flowered. 



Leaves, or their lobes, spinulose-denticulate ; stem leafy below. 



Leaves entire to pinnatifid, the teeth not spinulose ; stem leafy to the inflorescence. 

 Leaves hirsute or bristly on the veins beneath. 



Plant hirsute below ; leaves pinnatifid or the upper entire. 4. L. hirsuta. 



Plant hirsute up to the inflorescence ; leaves merely dentate or denticulate. 



5. L. Steelei. 



1. L. virosa. 



2. L. saligna. 



3. L. ludoviciana. 



