86 Braun and Engelmanri's North American Equiseta. 



species is E. Bogotense, Humb., Bonpl. and Kunth. (Syn. E. 

 stipulaceum, Vaucher, and E . Jlagelliferum, Kunze.) 



6. E. limosdm, Linn. — Stems tall, erect, generally above with 

 simple branches, the sterile ones much elongated ; grooved, near- 

 ly smooth ; vallecular air-cavities none, the carinal ones small, 

 the central cavity very large ; sheaths adpressed, consisting of 

 about eighteen 1-carinate not furrowed leaves, with linear acute 

 blackish teeth nearly destitute of a membranaceous margin; 

 branches somewhat scabrous ; sheaths herbaceous, consisting of 

 about six leaves with linear-setaceous points. — E. limosum, and 

 E . Jluviatile, Hoffm. and other authors. E. Heleocharis, Ehrh. 



§. minus, A. Braun. Stems simple, somewhat scabrous, sheaths 

 consisting of about eleven leaves. — E. uliginosum, Muhlenb., 

 Willd. 



y. polystachyum. With numerous short verticillate, florife- 

 rous branches. 



Hab. In ditches and swamps in Europe. In the United States 

 in Pennsylvania, ( Wolle,) New York, (H. Eato7i,) and Wiscon- 

 sin, (Lapham in herb. Short.) @. in North America, Newfound- 

 land, (La Pylaie. ) Northern States, (Beck's Botany,) Pennsylva- 

 nia, (Muhlenberg,) Virginia, (Pursh.) Also in Germany in peat 

 morasses, (A. Braun.) Easily distinguished from E. palustre, 

 by the structure of the stem and by the teeth ; though at first 

 sight var. (?. considerably resembles some forms of the former. 

 The sheaths are composed of 10 to 22 leaves, commonly 17 to 

 20, in the American specimens examined by me of 15 to 21, in 

 @. of 10 to 12 leaves. Rhizoma never tuberous. The branches 

 are generally developed after fructification. 



$ 2. Equiseta stichopora, ( Winter-E quiseta) : Stomata dis- 

 posed in two distinct ranges on each side of the groove ; each 

 range formed by one or more rows of stomata. (All the 

 known species of this division, have hardy evergreen stems.) 



Most of the tropical Equiseta, as well also as some of the most 

 northern species, (E. scirpoides and E. boreale,) belong to this 

 large and very difficult division. They all contain more silex 

 beneath the cuticle than the E. speiropora, which accounts for 

 their hardness and durability. Their distinguishing characteris- 

 tic is the disposition of the stomata in two ranges, separated by 

 a free interstice. In the European and North American species, 



