NATURAL GROUPS. 11 



17. H. Gibsoni. 



18. H. argenteTun. 



19. H. nitidum. 



20. H. aggregatum. 



* * Styles more or less livid. 



21. H. murorum. 



22. H. csesium. 



23. H. steUigerum. 



24. H. vulgatum. 



d. Pseudo-accipitrinaB. — InTolucres sub-glabrous. Eoot-leaves fre- 

 quently fonmng a winter rosette, but rarely present wben the 

 plant is in flower. 



25. H. gothicum. 



III. ACCIPITIIINA.— Without true root-leaves. Forming in 

 autumn, at the base of the stem, closed buds, which the 

 next season, become leafy stems. Phyllaries in many rows. 

 Hairs of the pappus rigid, unequal. 



a. Pseudo-pulmonarese. — Occasionally forming small rosettes, similar 



in appearance to those of the Pulmonmreee, but not persistent 

 during winter. 



26. H. tridentatum. 



b. AphyUopodsB. — Never forming persistent rosettes. 



* Plorets minutely pilose or sub-glabrous at the tips. 



27. H. prenanthoides. 



28. H. strictum. 

 * * Plorets glabrous at the tips. 



29. H. umbeUatum. 



30. H. crocatum. 



31. H. rigidum. 



32. H. corymbosum. 



33. H. boreale. 



