Nov., 1912.] An Undescribed Equisetum from Kansas. 19 



AN UNDESCRIBED EQUISETUM FROM KANSAS.* 



John H. Schaffner. 



For many years the writer has known a pecuhar type of 

 Equisetum with annual, aerial stems, growing on clayey banks 

 and bluffs in central Kansas. This plant was referred to Braun's 

 Equisetum laevigatum, although some of its most evident charac- 

 ters did not agree with the description of that species. 



In 1903 (Fern Bull. 11: 40), Eaton stated that according to 

 his observations, E. laevigatum A. Br. was annual and this view 

 is continued in Gray's Manual, 7th Ed. 1908, where the state- 

 ment is made that the stems are "mostly annual." In a note in 

 the Ohio Naturalist, 4: 74, the writer agreed with Eaton and also 

 suggested that E. laevigatum as at present understood might be a 

 composite species. Eaton described E. hyemale intermedium 

 and stated that it was "often confused with E. laevigatum. " 



The writer has had the various forms of Equisetum, which are 

 involved in the confusion, under consideration since 1903 and has 

 come to some definite conclusions which are here presented : 



1. The annual form of Equisetum from the west usually 

 going under the name E. laevigatum A. Br. is an undescribed 

 species. 



2. Braun's description of E. laevigatum is essentially correct. 



3. Eaton's E. hyemale var. intermeditim is Braun's E. 

 laevigatum. 



The writer examined the original material at St. Louis from 

 which Engelmann sent specimens to Braun, and found that the 

 plants agree well with Braun's description. They are perennial 

 and the cones have a definite point. They are considerably 

 smoother than the usual forms of E. hyemale but much rougher 

 than the disputed plants from Kansas. 



One of Engelmann's specimens of E. laevigatum A. Br. dis- 

 tinguished as variety B^ scabrellum, collected in August, 1843, on 

 the banks of the Mississippi below Jefferson Banks is marked in 

 pencil as "Probably type specimen." Both branched and un- 

 branched specimens are in the collection. This specimen has no 

 •cones. Another specimen labeled E. laevigatum A. Br. from 

 sterile hills near harbors nine miles west of St. Louis, July, 1844, 

 has the cone with a rigid point and agrees with the specimens the 

 writer identified as E. laevigatum, the past summer in a trip to 

 Kansas. It has the long dilated sheath and other distinguishing 

 characters. 



*Contribution from the botanical laboratory of Ohio State University, 

 No. 70. 



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