1920] Wiegand,—Eupatorium purpureum and its Allies 61 
In the Species Plantarum, on the page preceding that on which 
E. purpureum was described, Linnaeus proposed another species 
under the name LE. trifoliatum. The original description consists 
solely of the statement “foliis ternis," which plainly is insufficient 
to define the species; and it is therefore necessary to depend upon the 
citations given, which are to Gronovius and Ray. The description 
given by Gronovius is inconclusive, having been drawn apparently 
from a slender shade plant with whitish heads without stating such 
characters as are of value here. The Clayton plant cited by Grono- 
vius is his No. 620. A photograph of a specimen now in the British 
Museum labelled Clayton No. 620 shows it to be probably our No. 3. 
The leaves are lanceolate, bluntly and finely toothed; and, so far as 
can be made out from the print, the stem is purple and glaucous 
and not darker at the nodes. "The stem is also cracked in one place 
in a manner more likely to occur if it were hollow. Also, as has al- 
ready been stated, No. 3 is more likely to have been found by Clayton 
than No. 4. However, no species normally has leaves of this form in 
3's. The specimen seems abnormal, but is more reasonably placed 
in No. 3. E. trifoliatum L. and E. purpureum L. are therefore to 
be considered one and the same species. Most of the early writers 
retained E. trifoliatum in addition to the various names employed 
by them for the other species. So far as the writer is aware, Torrey 
and Gray (Fl. N. A. ii. p. 82, 1841) were the first to unite E.trifoliatum 
and E. purpureum. This was done under the latter name; which, 
therefore, is the one to be retained under the Vienna Code (Chapter 
III, Sect. 5, Art. 46) which says: “ When two or more groups of the 
same nature are united, the name of the oldest is retained. If the 
names are of the same date, the author chooses, and his choice cannot 
be modified by subsequent authors." 
'The oldest name that may be legitimately applied to our species 
No. 1 is the E. verticillatum of Lamarck (Encyc. ii, 405, 1786). This 
was divided by the author into two parts, x and $8. Lamarck’s 
citations and descriptions do not entirely agree. The Cornut and 
Morrison citations under g are the ones listed by Linnaeus under 
E. purpureum a, and have been shown above to refer to our No. 3. 
The Hermann reference under ĝ, as has already been pointed out, 
refers to No. 1. However, the description given by Lamarck 
shows that both g and @ are to be referred to species No. 1. In this 
description reference is made to a dull-green dotted stem and purple 
