Some Recent Fern Literature 
Professor F. K. Butters, of the University of Minne- 
sota, has recently published! a thorough-going tax- 
onomic study of the American lady-ferns. In dis- 
tinguishing species, he has placed little weight on details 
of the form and cutting of the frond, taken by them- 
selves, but has sought more reliable characters in indusia, 
scales, spores and the like. His conclusions may’ be 
Summarized as follows: 
- The genus Athyrium is abundantly distinct from 
Asplenium, with which it has been, until recent years, 
united by American authors, but, as already pointed 
out by Milde and Copeland, is closely related to, and 
hot very clearly separable from, the tropical genus 
Diplazium. It is also closely related to the more primi- 
tive species of Dryopteris, and probably arose from 
Some form similar to D. Thelypteris. 
2. The silvery and narrow-leaved spleenworts, which 
have been more or less handed back and forth between 
Asplenium and Athyrium in recent manuals, really 
elong in neither, but should find a resting-place in 
Diplazium. 
3. The lady-fern of the Northwest, Athyrium cyclo- 
serum Rupr., is identical in all essential respects with 
the original A. Filix-femina of Europe and should bear 
that name. The eastern lady-ferns fall into two species, 
distinet from each other and from true A. Filia-femind. 
For the benefit of our readers who may be interested 
and who may not have access to Prof. Butters’s pape? 
the names and ranges of the three American species 
oad 4 synopsis of their characters, as worked out by 
him, are given below. 
a 7 
" Butters, Frederic K. Taxonomic and Geographic pion pinee 
Selggen Ferns. _I. ‘The Genus Athyrium and lace! ae pane 
ite An, led to Athyrium Filix-femina. II. page sai OL 138. SeDtes 
lai7, “2” Varieties. Rhodora 19: 170-216, figs 
53 
