THE HORSETAILS. 59 



produces before fruiting, it does not put forth its 

 catkins until several other species have shed their 

 spores. As its name implies, this species is usually 

 found in several inches of water, and the rootstock, 

 lying in the unfrozen mud, early feels the vernal impulse 

 and starts the young stems upward soon after the ice 

 has disappeared and while yet the meadow grasses are 

 brown and sere. These developing stems are most 

 striking objects, being ringed at close intervals with 

 many circles of the black saw-like teeth of the sheaths. 

 Sometimes as many as thirty circles of teeth may be 

 found on the stem before it has pushed above the sur- 

 face of the water. Growth, as in the other species, is 

 principally a matter of lengthening internodes. 



About the last week in May, in the southern part of 

 its range, the stems that are to produce the spores 

 develop a frui ting-catkin an inch or more in length and a 

 third as thick. Fertile fronds are ordinarily not abun- 

 dant, but* it is said that a period of drouth will greatly 

 increase their numbers. As soon as the spores are shed, 

 this catkin withers, but from the sheaths of the stem 

 that bears it slender branches have been developing, and 

 these, lasting through the season, make the stems look 

 so much like the regularly sterile ones that they cannot 

 be distinguished from them at first glance. Since the 

 production of spores is a heavy draft upon the vigour of 

 the stem, the fertile fronds are usually overtopped by 

 the others, which often reach a height of five feet or 

 more. 



There is no uniformity in the manner of branching, as 

 in most other species, but each stem is likely to vary the 

 pattern somewhat. In general, however, the lowest ten 

 or twelve joints are unbranched, then come several 



