Genus 36.] 



I 



THISTLE FAMILY. 



391 



Leptilon Canadense TL.) Britton. 

 Horse-weed. Canada Fleabane. 

 (Fig. 3827.) 



Erigeron Canadensis L. Sp. PI. S63. 1753- 



Stem hispid-pubescent, or glabrate, 3'-io° 

 high, the larger plants paniculately much 

 branched. Leaves usually pubescent or ciliate, 

 the basal and lower spatulate, petioled, incised, 

 dentate or entire, \'-\' long, obtuse or acutish, 

 those of the stem linear and mainl)- entire; 

 heads usually very numerous; about 2" broad; 

 involucre campanulate, \"-i)i" high, its 

 bracts linear, acute, glabrate, the outer shorter; 

 rays numerous, white, shorter than the pappus 

 and mostly shorter than their tubes. 



In fields and waste places, a common weed 

 throughout North America except the extreme 

 north. Widely distributed as a weed in the Old 

 World and in South .\merica. Called also Butter- 

 weed, Prideweed, Fireweed, Bloodstaunch.Cow's- 

 or Colts-tail, Bitter.weed. June-Nov. 



2. Leptilon divaricatum (Michx.) Raf. 



Low Horse-weed. Purple Horse -weed. 



(Fig. 3828.) 



Erigeron divaricatus Michx. Fl. Bor. Am. 2: 123. 1803. 

 Leplilon divaricalum Raf. Fl. Tell. 2: 265. 1S18. 



Stem diffusely much branched, 3'-i2' high, pubes- 

 cent or hirsute. Leaves all linear or subulate, entire, 

 4"-i2" long, about }'■." wide, the uppermost minute; 

 heads numerous, about 1" broad; involucre campanu- 

 late, \" high, its bracts linear, acute, pubescent, the 

 outer shorter; rays purplish, shorter than their tubes. 



In sandy soil, especially along rivers, Indiana to Minne- 

 sota, south to Tennessee, Louisiana, Nebraska and Texas. 

 June-Oct. 



37. DOELLINGERIA Nees, Gen. & Sp. Ast. 176. 1832. 



Perennial leafy herbs, the lower leaves reduced to scales or sheaths, the upper large, 

 tnostly entire, acute or acuminate in our species. Basal leaves none. Heads corymbose, usu- 

 ally numerous; involucre campanulate to hemispheric, its bracts imbricated in several series, 

 appressed, thin, sometimes scarious-margined, their tips not herbaceous nor foliaceous. 

 Receptacle foveolate. Ray-flowers white, pistillate, not very numerous. Disk-flowers per- 

 fect, the corolla with a slender tube abruptly expanded into a campanulate 5-lobed limb, 

 white to greenish in our species. .Anthers obtuse at the base; style-appendages ovate to sub- 

 ulate I rarely obtuse 1. Achenes obovoid, glabrous, or pubescent. , Pappus double, the outer 

 series of numerous short bristles or scales, the inner series of long capillary bristles, some 

 or all of which have thickened tips. [In honor of Th. Dollinger, botanical explorer.] 



About 4 species, natives of eastern North America. 



Leaves lanceolate to ovate; heads mostly numerous. 



Leaves lanceolate to oblong-lanceolate, acuminate. 



Leaves ovate to ovate-lanceolate, acute. 

 Leaves, at least the lower, obovate ; heads commonly few. 



1. D. umbellata. 



2. D. humilis. 



3. D. infirma. 



