RYDBERG: Rocky MOUNTAIN FLORA 461 
tana. The other specimen is a duplicate of the type of A. mollis, 
received from Hooker. This is almost identical with A. subplu- 
mosa Greene, or A. Chamissonis longinodosa A. Nels., except that 
the involucral bracts are broader, oblanceolate, and abruptly 
short-acuminate. It represents a plant not uncommon in the 
Rockies, from northern Wyoming northward. The Arnica that 
is not uncommon in New England was referred to A. Chamissonis 
in Gray’s Manual, 6th edition, and to A. mollis by Robinson & 
Fernald in the Gray’s New Manual. It has nothing to do with the 
former. It is related to the latter, but is, I think, distinct enough. 
It has more affinity to A. amplexifolia Rydb. (A. amplexicaulis 
Nutt.) and A. rivularis Greene than to A. mollis Hook. It does 
not have the broad bracts of A. mollis. It should be known as 
Arnica lanceolata Nutt. A duplicate of the type (if not the ac- 
tual type) of the last named is found in the Torrey herbarium. 
What Professor Nelson had in mind ‘as Arnica mollis when pre- 
paring the manuscript of the New Manual, I can not imagine. 
In his key he separates it from Arnica subplumosa by the “‘leaf 
blades decurrent on the petioles.”” The blades are slightly and 
but slightly decurrent in both. His description is very vague 
and evidently drawn from several species. As synonyms he cites 
“A. Chamissonis in. part, but mostly A. latifolia as to our range 
(A. latifolia A. Gray, Bot. Calif. 1: 415. 1885; A. tomentulosa 
Rydb. loc. cit.28: 20. 1got).’”’ It is true that Gray and others re- 
ferred A. mollis to A. Chamissonis, but I do not know that it 
has been referred to A. latifolia, unless by Prof. Nelson. Arnica 
latifolia A. Gray in the Botany of California comprises A. latifolia 
Bong., A. Menziesii Hook. (this perhaps not specifically distinct 
from A. latifolia) and A. diversifolia Greene ( A. latifolia viscidula 
A. Gray). None of them has anything to do with A. mollis. 
A. tomentulosa Rydb. is related to A. Chamissonis Less., but differs 
in the short pubescence and the broad involucral bracts, rounded 
at the apex. If the form of the bracts should happen to be a 
variable character and of no specific value, Nelson’s own Arnica 
rhizomata should be reduced to a synonym of A. fomentulosa, as 
there are practically no important differences except the form of 
the bracts and the latter name is nearly five months older. 
Greene’s idea of Arnica Chamissonis is also wrong. He states — 
