125. COMPOSITAE 271 



65. Tragopogon L. — Oyster-plant. Salsify 



1. Flowers purple; bracts lontrer than the flowers; peduncle thickened 

 below the head; fruiting in\olucre 3-5 cm long; roadsides and 

 fields, occasional; nat. from Eur. June-Aug. Vegetable Oyster. 

 (T. porrif alius x prat crisis is reported from Kane Co. by E. E. 



Sherff) T. porrif alius L. 



1. Flowers yellow. 



2. Bracts usually 13, longer than the pale lemon-yellow flowers; 

 peduncles thickened beneath the fruiting head ; fruiting in- 

 volucres 4.5-6 cm long; roadsides and fields, common; nat. 



from Eur. May-Oct 7\ dubius Scop. 



2. Bracts usually 8 or 9, equalling or shorter than the chrome- 

 yellow flowers; peduncles slender, scarcely thickened be- 

 neath the head; fruiting in\olucres 3-4 cm long; roadsides 

 and fields, common; nat. from Eur. May-Oct. Yellow Goats- 

 beard T. pratensis L. 



66. Lactuca L. — Lettuce 



1. Achenes slender-beaked; pappus white. 



2. Achenes light brown, 5- to 7-ribbed, the beak filiform, longer 

 than the body; stem 30-60 cm tall; flowers yellow. 

 3. Leaves elliptical in outline, pinnatifid, or merely spinulose- 

 denticulate in f. i?itcgrifalia (Bogenh.) G. Beck, tending 

 to turn edgewise in a vertical position, the margins and 

 midribs spinulose; panicle open, with spreading branches; 

 waste places, fields, and roadsides, common ; nat. from Eiu". 

 July-Sept. Prickly Lettuce L. scariola L. 



3. Leaves linear-lanceolate, or pinnatifid, their margins and 



midrib not spinulose; panicle narrow, with short ascend- 

 ing branches ; roadsides and waste places, occasional ; nat. 



from Eur. July-Aug. Willow Lettuce L. saligua L. 



2. Achenes dark brown, 1 -nerved, transversely rugulose, the beak 



about as long as the body or shorter; stem 1-3 m tall; native 



species. 



4. Leaves entire to pinnatifid, not spinulose-toothed; flowers 



yellow; open woods, fields, roadsides, common. June-Aug. 

 Wild Lettuce. A supposed hybrid between this and the fol- 

 lowing species has been collected in Cook Co 



L. canadensis L. 



4. Leaves spinulose-toothed, the midvein on the lower surface 

 somewhat setose; flowers pale lilac; prairie soil, rare. July. 



[L. campestris Gi'eene] L. ludaviciana (Nutt.) Riddell 



1. Achenes beakless or short-beaked; flowers not yellow. 

 5. Pappus white; flowers lavender or blue. 



6. Heads 6-10 mm in diameter, the in\olucies 10-13 mm high; 

 leaves varying from dentate to usually lyrate-pinnatifid 

 with the triangular terminal lobe larger; plants biennial 



