The American Midland Naturalist 
PUBLISHED BI-MONTHLY BY THE UNIVERSITY 
OF NOTRE DAME, NOTRE DAME, INDIANA 
VOL. VIII. MARCH, 1922. NO. 
nN 
. 
Seasonal Dimorphism in Arisaema Triphyllum. 
THEO. HOLM. 
(With 5 figures drawn by the author.) 
Along the Maryland Pike from Silver Hill to Clinton, 
Prince George County) are several tracts of woodland, mostly 
with Liriodendron, Liquidambar, Nyssa, Acer rubrum and var- 
ious oaks. There are many creeks and frequently, during the 
winter months, large areas of the woods become inundated. 
There is a luxuriance of ferns, notably Woodwardia areolata, 
Asplenium Filix-femina, Polystichum, Onoclea_ sensibilis, 
Dicksonia, Osmunda, and even the rare Ophioglossum vulga- 
tum is quite abundant. ‘: 
But when the Spring commeices there is no trace of Podo- 
phylum, Sanguinaria, Claytonia, Anemonella, Dentaria, 
Erythronium or Osmorhiza; the vernal Grasses are scarce. 
But there are many Carices, and Symplocarpus is at its very 
best, not to speak of Viola cucullata, Oakesia, and Rhus Tox- 
icodendron, while Orontium follows the creeks. Not until 
late does Arisaema triphyllum appear in these surroundings, 
and when it commences to bloom, the plant on the Potomac 
shore near Washington has passed flowering more than a 
month earlier. 
When finding this plant near Clinton barely in bloom in the 
middle of May, its remarkable low stature attracted my atten- 
tion, beside the late time of its appearance. “Nana” or “Sero- 
tina” would have seemed an appropriate name, but it so hap- 
pened that the plant proved to be the variety pusilla already 
described by Peck,’ and recently raised to specific rank: 
A pusillum (Peck) Nash in Britton’s manual. 
However, considered as a mere variety or at least as a form 
this plant seems more interesting than as a new species. It 
actually indicates how a species may be developed, and from 
1 Report New York state Museum 51: 297. 1897. 
