Dp 
RYDBERG: Puy D APHICAL NOTES 97 
parents as some existing circumpolar-arctic plants. While one 
offspring has remained arctic, 7. e. has not spread south during the 
glacial period or else has died out in the alpine regions, the other has 
become both alpine and arctic with a purely American distribution, 
or else the latter has developed from the former since glacial time. 
Such plants are: 
NortH AMERICAN ARCTIC-ALPINE CIRCUMPOLAR ARCTIC 
Chrysosplenium tetrandrum C. alternifolium 
Antennaria media A. alpina 
"4 ntennaria umbrinella A. alpina 
A few strictly arctic plants have for some reason spread into the 
Rockies, their existence there being a little hard to explain. 
Among these may be mentioned Phippsia algida, which has been 
collected in one place in Colorado. It is otherwise not known 
out of the arctic. Sagina nivalis has been found in Colorado; 
otherwise only in the arctic regions of America and in the Scandi- 
navian mountains. 
The following are truly endemic American arctic-alpine plants 
without any close relatives as far as I know elsewhere: 
Ranunculus hyperboreus *Erigeron compositus and its close 
relatives, viz. 
Aragallus podocarpus *Erigeron multifidus 
*Vaccinium caespitosum Erigeron trifidus 
The following are probably derived from subarctic or subalpine 
species: 
*Calamagrostis Langsdorfiit C. canadensis, American, subalpine 
and boreal. 
*Alsine laeta A. longipes, American, subarctic, sub- 
alpine and boreal. 
*Kalmia microphylla K. glauca, eastern American, sub- 
arctic and boreal. 
*Senecio cymbalarioides S. aureus, eastern American, boreal. 
” This j is also found in subarctic Scandinavia. 
