230 



WEEDS OF THE FARM AND GARDEN 



apex, or in sterile flowers, usually entire ; fruit a dry, inde- 

 hiscent achenium containing a single seed without endo- 

 sperm. The largest order of flowering plants consisting 

 of 840 genera and 13,000 species and found in all parts of 

 the world. Sometimes divided into the sub-families 

 Cichoriacese, Ambrosiaceae and Composite. 



Ironweed (Vernonia noveboraccnsis, Willd.). A rather 

 tall perennial herb, with leafy stem ; leaves long-lanceo- 

 late to lance-oblong; heads discoid 

 in open cymes ; scales of involucre 

 usually purplish, ovate or lance-ovate, 

 tipped with a slender cusp or awn ; 

 flowers purplish. From New Eng- 

 land to Minnesota and Kansas. V. 

 altisslma is a tall perennial, with heads 

 in loose cymes ; scales of involucre 

 obtuse or mucronate; flowers pur- 

 plish. Occurs from Pennsylvania to 

 Missouri and southwest. V. Baldwinil 

 is a minutely hairy plant with small 

 heads ; leaves lance-oblong or ovate ; 

 scales of involucre acute or acumi- 

 nate; flowers purplish. Occurs from 

 Minnesota to Texas. V. fasciculata 

 Fig. 144.. Ironweed has crowded linear or oblong-lanceo- 

 (VernoniaBaldivinii). late leaves; heads many flowered; 

 flowers purplish. Found in low grounds. 

 Thoroughwort (Eupatorium serotinum, Michx.). A 

 branched perennial with pubescent stems, three to seven 

 feet high ; leaves ovate-lanceolate, triple-nerved, coarsely 

 serrate ; heads in broad cymose clusters seven to fifteen- 

 flowered ; scales of involucre pubescent ; flowers white, 

 common southward, also in Iowa, Missouri, Kansas and 

 from Texas east to Florida and Delaware. The white 

 snakeroot (E. ageratoides) is a smooth, branching peren- 

 nial with broadly ovate, pointed leaves; compound 



