sirKGENEsiA NECESsARtA. Ambrosia. S9l 



On the banks of ponds and ditches : Pensylvania and 

 Virginia. O- J^^b' — Sept. v. v. The flowers of 

 this genus are very inconspicuous. 



2. A. hirsntissima ; fohis arete sessilibus simplicibus oblon- Udentata, 



gis supra basin latescentem utrinque unidentatis, fruc- 

 lu tetragono infra apicem quadrispinoso. Mich. _fi. 

 amer. 2. p. 182. 

 In the western parts of the Allegany mountains © . 

 July — Sept. V. V. 



3. A. hirsuta, aspera ; foliis 3-lobis serratis, lobis ovali-lan- trifida. 



ceolatis acutninatis, fructu infra apicem G-spinoso. — 

 IViltd. sp.pl. 4. p. 375. 



Icon. Moris, hist. 3. s.6. t. \.f. 4. 



On the banks of rivers and ditches : Pensylvania to Ca- 

 rolina. O- Aug. Sept. V. V. From five to eight 

 feet high. 



4. A. foliis bipinnatifidis glabriusculis, petiolis longe cilia- elatior. 



tis, racemis terminalibus paniculatis, caule virgato. 

 lFilld.sp.pL4.p.376. 

 In old fields : Canada to Carolina. G- June— Aug. v. v. 



5. A. foliis bipinnatifidis subtus canescentibus summis pin- artemisifolia,. 



natifidis, racemis ternis terminalibus, rarais fastigiatis. 

 Willd. sp. pi. 4. p. 376. 

 In fields and waste grounds : Pensylvania to Carolina. 

 O- Aug. Sept. V. V. 



6. A. foliis glabris bipinnatifidis summis pinnatifidis, race- paniculata. 



mis terminalibus soliiariis, ramis fastigiatis. IViltd. sp. 



pi. 4. p. 376. 

 Icon. Pluk. alm.t. 10./. 5. 

 Jn old fields and on road sides : Canada to Florida. O- 



July — Sept. V. V. 



7. A. foliis caulinis pinnatifidis subdentatis petiolatis^ rameis heterophyUa. 



summis lanceolatis sessilibus, petiolis longe ciliatis, 

 racemis terminalibus solitariis, caule paniculate. 

 IV Hid. sp. pi. 4. p. 37s. 

 On the banks of rivers and ditches : near Philadelphia. 

 O. July — Sept. p.v. 



667. XANTHIUM. Gen. pi. 1426. 



1. X. caule inermi ramoso, foliis cordatis lobatis serratis StTumarium, 

 scabris basi trinervibus, fructibus ellipticis pubescenti- 

 bus setis rigidisuncinatis. — JVilld. sp. pi. 4. p. 373. 



