COMPOSITE FAMILY COMPOSITAE 
LATE-BLOOMING THOROUGHWORT 
Eupatorium serotinum Michx. 
The Late-blooming Thoroughwort is most frequently mistaken. 
for the very poisonous White Snakeroot, page 341; therefore the 
differences between them should be carefully noted. This species 
usually does not begin 
blooming until September 
and continues until killed by 
frost. Sometimes it grows in 
woods but is more often 
found in open places and in 
moist soil, such as river 
bottomland, from Delaware 
to Minnesota and south to 
Florida and Texas. 
The stem is much 
branched and densely cov- 
ered with fine hairs, much 
more so than White Snake- 
root ever is. Also, it is taller, 
growing 4-8 feet high. All” 
the leaves are slender pet- 
ioled, lanceolate or ovate 
lanceolate, sharply toothed | 
and 3-6 inches long, but on 
the average are narrower 
than those of the White 
Snakeroot, being from one- 
! half inch to 2 inches wide. 
f They are 3-nerved but have 
a tendency to be 5-nerved at the base. Furthermore, although: 
most of them are opposite, the upper ones are alternate and this 
is never true of White Snakeroot. 
The heads are very numerous, the inflorescence being broadly 
cymose and about one-quarter inch high. The involucre is bell 
shaped and its narrowly oblong and hairy bracts are arrange 
in 2 or 3 series of very unequal length. There are 7-15 flowers in 
each head, and they are white but not pure white as are those o 
White Snakeroot. 
338 
