204 Lake Maxinkuckee, Physical and Biological Survey 



along the railroad south of the lake. It also grows in low woods 

 among the brush. It has a world-wide distribution and was orig- 

 inally described from Europe. It was observed commonly up well 

 by May 12. The spores ripen in August. 



FAMILY 4. EQUISETACE^E. HORSETAIL FAMILY 

 20. FIELD HORSETAIL 



EQUISETUM ARVENSE L. 



The Field Horse-tail has a very wide distribution, ranging 

 through the northern part of North America, Europe and Asia. It 

 is usually found in sandy soils along roads and railroads. Rail- 

 road embankments form a favorite habitat and on high steep 

 slopes where the railroad has been graded up considerably the 

 peculiar pale fertile fronds of this species, looking somewhat like 

 odd mushroom growths of some sort, make conspicuous patches in 

 early spring, and are followed later, after these have withered 

 away, by the symmetrical little conical sterile plants which look 

 like miniature evergreens. The peculiar distribution of the species 

 in this country, along* the well trodden ways of civilization and 

 travel, points to the possibility that it may be an introduced species, 

 the spores perhaps, carried with the dust of trade. At the lake 

 it was most abundant along the railroad and along the road down 

 by Farrar's. 



The fertile fronds have a rather long season in spring, com- 

 ing up in favorable localities considerably earlier than in others. 

 By April 15, 1901, the spores were ripe by Farrar's. By April 

 17, plants along the railroad by Winfield's were up abundantly, and 

 by April 26 the spores along the railroad south of the lake were 

 nearly all shed. The sterile shoots began to appear April 28. 

 There is considerable difference in the appearance of the indi- 

 vidual sterile fronds ; some leaves which form the fringing being 

 absent, so that the node is unfringed. The form in which the 

 whole plant is nearly prostrate (var. decumbens Meyer) is quite 

 frequent. On September 28, 1906, some of the green, branching 

 fronds along the railroad back of the cornfields were observed bear- 

 ing cones of fruit. These represent the variety serotinum. On 

 moist mornings in autumn the tips of the branches of the sterile 

 plants were observed heavily covered with transpiration drops, 

 showing that physiological activities had been going on quite ac- 

 tively at the time. The fronds were observed still quite green as 

 late as November 19. 



