1920] Mackenzie,—Purple-flowered Eupatoriums 163 
EUPATORIUM TRIFOLIATUM L. 
The first species of this group described if page priority is taken 
into consideration is the above species. The description (Sp. Pl. 
837) reads as follows: 
*9. EUPATORIUM foliis ternis. 
* Eupatorium caule erecto, foliis ovato-lanceolatis serratis petio- 
latis ternatis. Gron. virg. 178. 
* Eupatorium cannabinum, foliis in caule ad genicula ternis, mari- 
landicum. Raj. suppl. 189. 
* Habitat in Virginia." 
Nothing of value is to be found in the description of Ray, but the 
description of Gronovius deserves full quotation. It is as follows: 
*EUPATORIUM caule erecto: foliis ovato-lanceolatis, serratis, petio- 
latis, ternatis. 
* Eupatorium floribus albis, in panicula laxa terminatrice dis- 
positis: foliis ovato-lanceolatis, petiolatis, ad genicula semper ternis, 
per intervalla haud semipedalia a se invicem distantibus: caule 
singulari non ramoso. In solo pingui & umbrosis locis inter Verb- 
esinas et Serratulas initio Augusti floret. Clayt. n. 620.” 
Prof. Wiegand identifies the above rather doubtfully with Species 
No. 3, basing his identification on a photograph of Clayton's 620 
from the British Museum. He says “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 already 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." 
It seems to me that this identification is unfortunate and that in 
making it the description from Gronovius has not been given due 
consideration. When it is considered that Species No. 3 is the 
largest of all our purple-flowered Eupatoriums and is characterized 
by its narrow leaves in 5’s or 6’s and that it rarely has leaves in 3's 
and then only near the flowers—never in my experience in the main 
whorls—one can well understand the dislike I feel to applying the 
name Eupatorium trifoliatum to this plant. But this does not seem 
to me to be the proper course. As far as I can see the name applies 
to Species No. 4 or possibly a closely allied species. In support of 
this view the following points are to be noted. 
