COMPOSITAE. 



VOL. III. 



2. Petasites trigonophylla Greene. 

 Arctic Sweet Colts foot. Fig. 4596. 



Petasites trigonophylla Greene, Leaflets i : 180. 

 1906. 



Scape very scaly, 3'-io' high. Leaves 

 deltoid- reni form to ovate-orbicular in out- 

 line, 2'-6' long, irregularly lobed, green and 

 glabrous above, persistently white-tomen- 

 tose beneath, the lobes few-toothed; heads 

 corymbose, the inflorescence about 4' long; 

 involucre campanulate; flowers nearly 

 white, the marginal ones of the pistillate 

 heads radiate. 



Wet grounds, Quebec, Minnesota and Sas- 

 katchewan. June-Aug. 



Petasites frigida (L.) Fries, admitted, in 

 our first edition, as recorded from Lake Win- 

 nipeg, is a high boreal species, not known to 

 occur within our area. 



3. Petasites sagittata (Pursh) A. Gray. 

 Arrow-leaf Sweet Coltsfoot. Bitter- 

 bur. Fig. 4597. 



Tussilago sagittata Pursh, Fl. Am. Sept. 332. 1814. 

 Nardosmia sagittata Hook. Fl. Bor. Am. i : 307. 1833. 

 Petasites sagittata A. Gray, in Brew. & Wats. Bot. 

 Cal. i : 407. 1876. 



Scape and racemose-corymbose inflorescence 

 similar to those of the two preceding species. 

 Leaves deltoid-ovate to reni form-ovate, persist- 

 ently white-tomentose beneath, glabrous or nearly 

 so above, 4'-io' long, their margins sinuate-den- 

 ticulate, neither cleft nor lobed ; involucre cam- 

 panulate ; flowers nearly white, the marginal ones 

 of the pistillate heads radiate. 



In wet grounds, Labrador to Hudson Bay, Manitoba 

 and Minnesota, west to British Columbia, south in the 

 Rocky Mountains to Colorado. May-June. 



4. Petasites Petasites (L.) Karst. 



Butter-bur. Butterfly-dock. 



Fig. 4598. 



Tussilago Petasites L. Sp. PI. 866. 1753. 

 Petasites officmalis Moench. Meth. 568. 1794. 

 Petasites vulgaris Desf. Fl. Atlant. 2: 270. 1798. 

 P. Petasites Karst. Deutsch. Fl. 1062. 1880-83. 



Scape very scaly, 6'-is' high. Leaves orbicu- 

 lar or hastate-reniform, often 12' broad when 

 mature, rounded or pointed at the apex, repand- 

 denticulate all around, persistently white-to- 

 mentose beneath, green and mostly glabrous 

 above; heads 4"-6" broad, mostly dioecious, 

 in a dense raceme, the statninate ones smaller 

 than the pistillate ; flowers pink-purple, fra- 

 grant, none of them radiate. 



In cultivated and waste ground, eastern Penn- 

 sylvania and Massachusetts. Naturalized from 

 Europe. Native also of northern Asia. Batter- 

 or flea-dock. Bog- or poison-rhubarb. Eldin. 

 Gallon. Umbrella-leaves. Pestilence-wort. Ox- 

 wort. April. 



