THE HORSETAILS. 51 



resemblances it is curious that the range of Equisctum 

 Id mat da in America should be restricted to a narrow 

 strip of country on the Pacific coast, while Equisctum 

 arvcnse is spread over nearly the whole continent. The 

 two may thus sometimes grow in the same locality, but 

 no intergrading forms have been found. When they grow 

 in company, Equisetum arvense appears to be a week or 

 more earlier than Equisetum tehnatcia. The time at which 

 the fertile spikes appear depends somewhat on the locality. 

 In California, according to Campbell, growth continues all 

 winter, and the fertile fronds, developing gradually, 

 spring up and spread their spores whenever they are ripe. 



In British Columbia the fertile spikes are produced 

 during the first warm days of spring, which occur about 

 the middle of April. In a short time they have reached 

 a height of from ten inches to two feet, with a diameter 

 of an inch or more. The stems are therefore the heavi- 

 est of any species in the North Temperate Zone. They 

 are reddish brown, contain thirty or more shallow 

 grooves, and at the joints are encircled by the large, 

 loose, light-brown sheaths, which, including the long, 

 slender teeth, are nearly two inches in length. The cat- 

 kins are two or three inches long, and three quarters of 

 an inch thick, and consist of twenty or thirty whorls of 

 sporophylls. 



The sterile fronds appear as the spores are being shed. 

 These are ordinarily about three feet high, though in 

 favourable situations they may attain to more than 

 thrice that height, in such cases being half supported by 

 the shrubbery among which they grow. Often they 

 grow in such masses that it is difficult to pass through 

 them. When the stems appear, the branches are short 

 and closely appressed, but later they spread out some- 



