296 ASTER FAMILY 



1. Leaves simple, oblong to linear and entire or 3- 



5-lobed at the tip T. Nuttdllii 



2. Leaves 3-5-parted into linear lobes, as a rule T. capitdtum 



TARAXACUM Haller 1768 DANDELION 

 (Gr. tarasso, to disturb, in allusion to its medicinal properties) 



Heads with yellow perfect strap-flowers, achenes oblong to linear- 

 spindle-shaped, 4-5-angled, roughened or spiny, tapering into a long beak, 

 pappus of hair-like bristles; receptacle flat, without chaff, involucre oblong 

 to bell-shaped, main bracts nearly equal in 1 row with several rows of outer 

 shorter spreading bracts ; heads solitary ; leaves basal, wavy-toothed to pin- 

 natifid ; perennial. 

 Leaves toothed to pinnatifid, sometimes nearly entire; 



flower-stalk 1-15 in. long; heads 1-2 in. wide T. officinal e 



TETRAD YM i A DeCandolle 1837 

 (Gr. tetradymos, four together, the heads often but 4- flowered) 



Heads without rays, the disk-flowers yellow or yellowish, perfect, 

 achenes cylindric, rounded, often very woolly ; receptacle flat, without chaff, 

 involucre oblong to cylindric, of 4-6 concave overlapping bracts; heads 

 cymose or clustered ; leaves alternate, entire, sometimes clustered, oocas- 

 sionally modified into spines, usually densely felted ; shrubs. 



1. Heads 4-flowered; involucral bracts 4-5; achenes 



hairy to smooth ; stems 1-2 ft. high 



a. Branches spiny T. Nuttdllii 



b. Branches not spiny ; white wool permanent or 



disappearing T. canescens 



2. Heads 5-9-flowered ; involucral scales 5-6 ; 



achenes white-woolly ; stems 2-4 ft. high ; 



branches spiny T. spinosa 



THELESPERMA Lessing 1831 THELESPERMA 



(Gr. thele, nipple, sperma, seed) 



PI. 39, fig. 3, 8. 



Heads with yellow neutral ray-flowers or none, disk-flowers yellow to 

 brownish, perfect, achenes linear to oblong, somewhat pappillose, pappus 

 of 2 barbed awns, sometimes none ; receptacle flat, with chaff, involucre 

 hemispheric to bell-shaped, the inner bracts united to the middle or above 

 into a cup, the outer short, narrow and spreading ; heads solitary on the 

 ends of the branches ; leaves opposite, entire and linear or finely dissected ; 

 annual or perennial. 



