COMPOSITAE 



COMPOSITE FAMILY 



TALL THOROUGHWORT 



Eupatorium altissimnm L, 



The Tall Thoroughwort is also sometimes mistaken for White 

 Snakeroot, page 341. It is less common than some of the other 

 species and grows in dry open places from Pennsylvania and 

 Minnesota, south to 

 North Carolina and Texas. 



This Thoroughwort re- 

 sembles the late-blooming 

 species on page 338, in 

 that the stems of both are 

 densely covered with fine 

 hairs, and the blooming 

 season, September to frost, 

 is the same for both. The 

 Tall Thoroughwort grows 

 4-8 feet high and is much 

 branched near the top. 

 Leaves, however, as well 

 as the height of the plant, 

 should serve to distinguish 

 it from White Snakeroot; 

 they are strongly 3-ribbed, 

 lanceolate, gradually ta- 

 pering below into a short petiole, rather thick and rough, toothed 

 only above the middle or possibly entire. The lower leaves are 

 opposite but the uppermost are alternate. 



The heads are crowded in the large inflorescence but each head 

 has only about 5 white flowers. The involucre is bell shaped and 

 its bracts are oblong, rounded or blunt and densely hairy. They 

 are arranged in about 3 series with the outer shortest. The akenes 

 are 5-angled and the pappus is composed of slightly roughened, 

 slender bristles. 



The Upland Boneset, Eupatorium sessilijolium L., has a tall, 

 smooth, branching stem which bears many ovate-lanceolate, serrate 

 leaves that are rounded at the base and always opposite and sessile. 

 The heads and inflorescence are much like those ot Tall Thorough- 

 wort, the former about three-quarters ot an inch high, and the bracts 

 linear-oblong. The plant is found in dry woods from Massachusetts 

 and Pennsylvania to Albama and Illinois. It blooms a tew weeks 

 earlier than the Tall Thoroughwort and lasts as long. 



339 



