1921] Flora of the Boston District, —XLVII 131 
others to 1911); Boston (C. E. Perkins, 1882). Adventive from saline 
regions of Europe. 
M. suAVEOLENS (Pursh) Buchenau. Roadsides, dooryards and 
waste places, frequent. 
MEGALODONTA. 
M. Beckii (Torr.) Greene. (Bidens Beckii Torr. See Pittonia iv. 
271, 1901). Ponds and slow streams; well distributed except in south- 
eastern towns. 
MICROSERIS. 
M. Dovciasn Gray. Woolwaste, N. Chelmsford (W. P. Alcott, 
1878). Specimen in herb. Peabody Acad. Sci. 
MIKANIA. 
M. scandens (L.) Willd. Rich soil along watercourses; frequent 
and usually abundant. 
ONOPORDUM. 
O. AcantuiuM L. Dry soil in waste places, occasional. 
PALAFOXIA. 
P. rEXaNA DC. Banks of Merrimac River, Tyngsboro (collector 
unknown, October, 1896). Specimen in herb. N. E. Botanical Club. 
Native in Texas and Mexico. 
PARTHENIUM. 
P. Hysreropuorus L. Dump, Lowell (C. W. Swan, Sept. 11, 
1881); waste from mills, Malden (F. S. Collins, Aug. 2, 1890). Adven- 
tive from the west. 
PETASITES. 
P. palmatus (Ait.) Gray. Purgatory swamp, Norwood (H. A. 
Young, May 30, 1878; other collectors since); swamp, Franklin (S. 
Harris, June 17, 1897). 
P. vurcanis Hill. Vacant lot in wet soil, Audubon Road and Brook- 
line Ave., Boston, abundant for several years, now gone; also escaped 
in Brookline and Dorchester. Native of Europe. 
