RypDBERG: Rocky MounTAIN FLORA 329 
these two numbers of the Boundary Survey are in both the her- 
barium of the Columbia University and that of the New York 
Botanical Garden. The structure of the marginal achenes distin- 
guishes B. Bigelovii at once from B. bipinnata. 
THELESPERMA 
In the description of Thelesperma ambiguum in Coulter & Nel- 
son’s New Manual, we find the following: ‘‘bracts of the outer 
involucre 8, subulate-linear, almost equalling or half the length 
of the inner,’’ etc. In Wright’s specimens, from which T. am- 
biguum was described, the outer bracts are ovate or elliptic, 
scarcely one fourth as long as the inner involucre. What is de- 
scribed in the New Manual is evidently T. intermedium Rydb. 
When I described the latter, I had known it for about ten years 
and had never been able to make it agree with Dr. Gray’s descrip- 
tion of 7. ambiguum in the Synoptical Flora. In the original 
publication of Thelesperma ambiguum no diagnosis is given, only 
a few characters distinguishing it from related species. In habit 
T. ambiguum resembles most JT. subnudum, having the creeping 
rootstock of that species, the long naked peduncles, and the leaves 
found near the base of the stem only. The range is given as 
Montana to New Mexico and Texas. This was probably taken 
from the Synoptical Flora. The specimens on which Dr. Gray 
extended the range to Montana belong to 7. marginatum, in 
many respects closely related to T. ambiguum but with discoid 
heads. T. ambiguum, as far as I know, is not found north of 
southern Colorado. TJ. intermedium, which is really described 
under the name of T. ambiguum in the New Manual, does not 
have a “creeping rootstock”’ (as Gray described T. ambiguum) 
but has a biennial or perennial taproot; and it has a leafy stem. 
As the authors of the New Manual did not at all consider the dif- 
ferences in the subterranean parts of T. ambiguum and T. inter- 
medium, it was natural that they would not consider the same 
parts in T. trifidum and T. tenue, which resemble each other much 
more closely, and we find the latter as a synonym of the former. 
Thelesperma marginatum Rydb. is ignored altogether, although in 
my Flora of Montana four collections from that state are cited. 
