532 _ COMPOSITAE. Vou. IIL. 
2. Petasites trigonophylla Greene. 
Arctic Sweet Coltsfoot. Fig. 4596. 
Petasites trigonophylla Greene, Leaflets 1: 180. 
1906, 
Scape very scaly, 3’-10’ high. Leaves 
deltoid-reniform 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. 1: 307. 1833. 
Petasites sagittata A. Gray, in Brew. & Wats. Bot. 
Cal. 1: 407. 1876. 
Scape and racemose-corymbose inflorescence 
similar to those of the two preceding species. 
Leaves deltoid-ovate to reniform-ovate, persist- 
ently white-tomentose beneath, glabrous or nearly 
so above, 4’-10’ 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. Pl. 866. 1753. 
Petasites officinalis Moench. Meth. 568. 1794. 
Petasites vulgaris Desf. Fl. Atlant. 2: 270. 1798. 
P. Petasites Karst. Deutsch. Fl. 1062. 1880-83. 
Scape very scaly, 6-15’ 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 staminate 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. 
