Sonchus 



COMPOSITAE 



1007 



Taraxacum laevigatum (Willd.) DC. 



o 50 



Map 2212 



Sonchus arvensis L. 



50 



Map 2213 



Sonchus arvensis. 

 vji glabrescens Guenth Grab, & Wimm 



1. Taraxacum palustre (Lyons) Lam. & DC. var. vulgare (Lam.) 

 Fern. (Taraxacum officinale Weber and Leontodon Taraxacum L.) 

 Dandelion. Map 2210. A frequent to common obnoxious weed found 

 throughout the state except in the southwestern part, where it is less fre- 

 quent. It is a common weed in lawns, orchards, and fields and along road- 

 sides. The outer series of involucral bracts of the variety are recurved 

 even in the bud while those of the species are appressed until maturity. 

 Although the species has not been reported west of Pennsylvania, it may 

 be found westward and in Indiana. 



Nat. of Eu. and Asia; throughout s. Canada and the U. S. 



2. Taraxacum laevigatum (Willd.) DC. (Taraxacum erythrospermum 

 Andrz. and Leontodon erythrospermum (Andrz.) Britt.) Red-seed 

 Dandelion. Map 2211. This species is frequent in northern Indiana 

 and is possibly well distributed in sandy soils throughout the state. 

 It prefers a more sandy soil than the preceding, although it is adaptive 

 as to habitat. Found in habitats similar to those of Taraxacum palustre 

 var. vulgare. 



Nat. of Eu.; Maine to Ont. and Alberta, southw. to N. C, Tenn., and 

 Wyo. 



9595. SONCHUS [Tourn.] L. Sow Thistle 



Flowering heads about 4 cm in diameter, orange to lemon yellow; achenes 2-3 mm 

 long; perennials with creeping rootstocks. 



Involucre and peduncles more or less glandular-setose 1. S. arvensis. 



Involucre and peduncles glabrous la. S. arvensis var. glabrescens. 



Flowering heads 1.2-2.5 cm in diameter, pale yellow; achenes 1-1.5 mm long; annuals. 

 Auricles of leaves acute; achenes transversely wrinkled and with more than 3 



longitudinal lines to a side 2. S. oleraceus. 



Auricles of leaves rounded; achenes not transversely wrinkled and with 3 longitudinal 

 lines to a side 3. S. asper. 



1. Sonchus arvensis L. Field Sow Thistle. Map 2212. Frequent 

 along U. S. Highway 12 south of Buffington, about 2 miles southeast of 



