Nov., 1912.] An Undescribed Equisetum from Kansas. 21 



In size and manner of growth this new species is closely allied 

 to E. hyemale, and the larger variety of E. robustum, but it is 

 easily distinguished by its smoothness, its long green sheaths, 

 with a narrow black limb, and its darker green color." 



This description seems to be quite accurate except is some 

 minor points. The color is usually not darker green than in E. 

 hyemale and the sheaths are usually though not always dilated 

 above. The color of the large Equisetums varies considerably 

 with the environment, and in some cases the young sheaths are 

 more or less dilated than the old ones. 



The new species may be characterized as follows : 



Equisetum kansanum n. sp. 

 Kansas Horsetail. 



Aerial stems usually l-2}/2 feet high, annual, very smooth, 

 15-30 grooved, usually without simple branches unless broken 

 off; color mostly light-green; surface of the ridges and grooves 

 with cross or diagonal bands; sheaths long, dilated above and 

 usually constricted at the base, green with a narrow black band 

 at the top; teeth deciduous; cones ovate or oblong-ovate, without 

 a point, the apex obtuse or merely acute. On upland clayey 

 banks along ravines and hillsides, growing in rather scattered 

 tufts. Name derived from Kansas where the species is common. 



Type locality, Bloom township, Clay County, Kansas. Speci- 

 mens also from Mancos, Colorado. Type and cotype 1 deposited 

 in the herbarimn of the Ohio State University, Columbus, Ohio. 



Equisetmn laevigatum and Equisetum kansanum form the 

 transition types between the large, evergreen scouring-rushes 

 like E. hyeinale and E. robustum on the one hand and the tall 

 annual horsetails, like E. fluviatile on the other. E. laevigatum 

 is perennial in Kansas although it often freezes down to near the 

 surface of the ground in severe winters. 



The habit of growth between the three species which are often 

 confused is quite characteristic. E. hyemale grows in dense 

 masses usually on creek and river banks and low places. E. 

 laevigatum is rather tall and is more open and separate in its 

 growth, abounding in Kansas, in sandy river bottoms where the 

 soil is well filled with clay or other fine material and at the base 

 of clayey bluffs. E. kansanum as stated above is also open and 

 scattered in growth and is found mainly on clay banks along 

 ravines and hillsides. They may be readily separated by the 

 following key: 



