WEEDS OP THE THISTLE FAMILY. 



167 



prickly points, inner bracts longer, linear ; flowers purple, pinkish or white. 

 Achenes light brown, smooth, J Inch long, tipped by a copious white 

 pappus. (Fig. 120.) 



Frequent in dense patches in northern Indiana in woodland and 

 other pastures, old fields and waste places, and along roadsides; 



scarce or wanting in the southern coun- 

 ties. June-Oct. This thistle has gained 

 the reputation of being one of the worst 

 of weed scourges which Europe has fur- 

 nished us, but in Indiana is less trouble- 

 some than the common thistle or fox- tail. 

 Many other weeds, especially the teasel, 

 tall thistle and bull nettle are mistaken 

 for it. Usually it is first introduced into 

 a new locality by the seeds, and then 

 spreads rapidly wherever it can find a 

 foothold. From other thistles it is best 

 known by its deep running perennial 

 rootstocks. more slender stems and 

 small compact heads. (See Fig. ,13, b.) 

 From the rootstocks, which lie usually 

 far below the ordinary depth of the fur- 

 rows, branches are being continually 

 sent to the surface, oftentimes through 

 3 feet and more of hard packed soil. 

 These branches produce basal leaves the first year and flowering 

 stems the second ; these stems, like those of other thistles, appearing 

 to die after their seeds ripen, but only dying down to the tinder- 

 ground stem. "Wherever it occurs the numerous branches and root- 

 leaves soon cover the ground, smothering out the grass and pre- 

 venting stock from grazing near them on account of their many 

 prickles. Like other perennial herbs it can only be destroyed by 

 starving out or otherwise killing the underground stems. Rem- 

 edies : mowing or deep hoe-cutting three times each season, in June, 

 August and September, then salting or applying coal-oil or 

 sulphuric acid; repeated salting and sheep grazing for 2 years. 

 In fields. cut the thistles when in full bloom as close to the ground 

 as possible, then plow deeply and sow to millet or Hungarian grass, 

 seeding heavily and harrowing; in September cut the hay, plow 

 again and seed with rye; the next May plow under the rye and 

 plant to corn or some hoed crop. Short rotation and thorough 

 cultivation of almost any crop with hoe will eventually eradicate 

 the thistle. 



Fig. 126. Showing horizontal roots, 

 yo'ing shoots and mature plant in flower. 

 (After Dewey.) 



