Ampvrican Fern Journal 
Vol. 11 JULY-SEPTEMBER 1921 No. 3. 
North American Species of ite een 
North of Mexico.' 
JOHN H. SCHAFFNER,. 
There still appears to be some confusion as to the 
characteristics, names, and distribution of the North 
American species of Equisetum. The writer has been 
making a study of these plants for many years, in fact 
ever since, as a boy, he was unable to make some of his 
specimens fit the descriptions in the manuals in use at 
the time. The greatest difficulty was experienced with 
E. laevigatum A. Br. (1), since the plant supposed to be 
this species did not fit the key nor the description in 
several fundamental respects; but because there were 
not enough names to go around, the specimens were 
accommodated with the names which seemed to fit most 
perfectly. After many years of uncertainty about the 
matter, the writer examined the original material at the 
St. Louis Botanical Garden, from which Engelmann had 
sent specimens to Braun, and found that the plants 
agreed quite well with Braun’s description. Similar 
specimens from Engelmann were also shown to the 
writer by Underwood from the collections at the New 
York Botanical Garden. As a result of this study, 
Equisetum kansanum (4) was described as a new species 
with annual, smooth stems and cones without a point. 
It also became evident that A. A. Eaton’s Equisetum 
hiemale intermedium (2) was identical with the earlier 
1 hg from the Department of Botany, The Ohio State University. 
No. 
vo ‘1, no. 2 of the JournaL, pages 33-64, plate 1, was issued Oct. 
T2, 1921.] 
