Brann and Engelmamfs North American Equiseta. 89 



of the Wabash and Ohio, and the Mississippi near St. Louis, also 

 on lakes and smaller streams in that region, ( G. Engelmann.) 

 Banks of the Missouri up to Eau-qui-coule River, ( Geyer in Ni- 

 collet's Expedition.) Also in the East Indies; Lahore, (Jacque- 

 mont, ) Pondicherry, {Belanger.) Varieties (?. and y. near St. Louis, 

 the first with the common form, the other with E. lavigalum, 

 on poorer soil. 



This stately species appears to take the place of E. hyemale in 

 the Mississippi valley, at least in its middle and southern parts. It 

 reaches a size of from three or four to even six feet, {Geyer.) The 

 largest specimens from Louisiana, have 44 to 48, those from the 

 Ohio and from St. Louis, have all from 37 to 41 carinas, and con- 

 sequently leaves. The species is distinguished from E. hyemale. 

 by its size, by the strictly simple row of tubercles on the ridges, 

 and by the 3-carinate (not 4-carinate) leaves. It is a remarkable 

 peculiarity that in old specimens, not only the teeth or points are 

 deciduous, but also the upper part of the sheath itself down to 

 the black girdle, giving the stems the appearance of the fossil 

 Calamites, with reduced dimensions. The branches of flower- 

 ing stems have usually 11 carinas, but branches of old decaying 

 stems, and young sterile shoots have 17 to 25 and more carinas. 



Var. §. offers no difficulties ; but y. approaches very closely, 

 rather too much so, to the next species, whence the name. It 

 has the same size and growth, but the sheaths appear to be shorter, 

 their leaves never 4-carinate, and the tubercles on the carinas of 

 the stem constantly in one row. This variety corresponds with 

 var. y. of the next species, both being much smaller than the 

 common forms, and much rougher also ; the roughness extending 

 to the points of the leaves and rendering them more persistent. 



9. E. hyemale, Linn. — Stems tall, erect, simple, rarely with 

 a few branches ; carinas rough with two more or less distinct rows 

 of tubercles ; grooves on each side with a single series of stomata ; 

 vallecular air-cavities lara:e, the carinal ones minute ; central cav- 

 ity large ; sheaths elongated, closely adpressed, with a black gir- 

 dle above the base, and a black limb, consisting of about 20 (in 

 the branches 9) narrowly linear, at base 1-carinate, above obsolete- 

 ly 4-carinate leaves, with linear-subulate deciduous points, which 

 leave a bluntly crenate margin. 



(9. paleaceum, A. Braun. — Stems smaller, sheaths with a black 

 limb, but mostly without a black girdle, consisting of 10 to 12 



Vol. xlvi, No. 1.— Oct.-Dec. 1843. 12 



