1058 



The two species are almost precisely alike in their localities and 

 mode of growth. The branched rhizomes, with their matted fibrous 

 roots, creep extensively amongst the mud at the bottom of pools, 

 canals, and slow streams : from these, in the spring, arise a minia- 

 ture forest of stems, expanding and fructifying as the summer 

 advances, and dying down in the autumn. In habit, E. fluviatile is 

 more slender and elongated ; E. limosum, stouter and more rigid in 

 texture. E. fluviatile, both in a barren and fertile state, is usually 

 furnished with numerous long, slender branches, which, in the fully 

 developed and characteristic form, are arranged in lax, irregular 

 whorls, spreading from the stem at a considerable angle ; naked 

 stems being nearly as unfrequent as in E. palustre. E. limosum is 

 frequently, or usually entirely, without branches ; when present, they 

 are not nearly so numerous as in the other species, and seldom much 

 exceed the internodes in length : the whorls are consequently less 

 dense, but are more regular, and the branches which compose them 

 only curve slightly at the base, and run upwards almost parallel 

 with the stem. Below the whorls, in E. fluviatile, are frequently 

 placed solitary, elongated, lateral branches, which attain a conside- 

 rable length, and have the internodes conspicuously developed. In 

 the compound form of E. limosum, solitary branches are less frequent, 

 and, when present, they are short and blunt compared with those of 

 E. fluviatile, and the sheaths approximate closely. The barren stem 

 of E. fluviatile is terminated by a long, slender, cord-like extension, 

 entirely without branches, which withers and decays whilst the 

 remainder is still green and vigorous. In E. limosum the termina- 

 tion is stronger, and narrows more gradually : when branches are 

 present, they extend upwards higher than in the other species. It 

 was once thought that the differences between grooveless acute, and 

 sulcate blunt ribs, which are conspicuous when the plants are in a 

 dried state, might furnish a distinctive character ; but each species 

 varies considerably in this respect. The sheaths at the base of the 

 branches, in both, are similar in shape ; but, whilst in E. limosum 

 they do not usually differ much in colour from the stem, except at the 

 point of their teeth, in E. fluviatile they are invariably coloured 



" Equisetum fluviatile, L. ! Caules toti slriati raro uudi, semper heterocladi ramis 

 numerosissimis, laxis, cauda sterili longa taxa fragile terminati. Spica tenuis aestivalis." 



" E. limosum, L. ! Apud nos in prius vix transit : caules ex magna parte iu vivo 

 Isevissimi ! simplissimi vel homocladi, ramis polygonis arrectis, apicc ajquulcs et cou- 

 formes. Spica crassa atra vernalis." 



