Braun and Engelmanri* s North American Equiseta. 91 



seven 4-carinate leaves ; the points persistent, ovate membranace- 

 ous, with fragile awns. 



@. reptans, A. Braun. — Stems small, procumbent at base, 

 sheaths consisting of about four leaves. — E. reptans, Wahienb. 

 in part. Wahlenberg comprises this variety and the following 

 species in his E. reptans. 



Hab. Northern Europe ; also on the Alps in Central Europe, 

 and along the rivers rising in them. Also in North America, Ni- 

 agara, {Dr. Kimiicutt, according to Torrey ;) Vermont, (J. Ca- 

 rey, according to Oakes.) In Prof. Short's herbarium, I have 

 seen a specimen from New York, which I cannot but refer here, 

 though the central cavity is much larger than the vallecular ones, 

 and the 8 carinss of the stems are nearly simple. In German spe- 

 cimens the sheaths have 6 to 8, rarely 9 to 10 leaves ; var. (?. grow- 

 ing only in higher latitudes, has four or five, very rarely only 

 three teeth. 



12. E. scirpoides, Michx. — Caespitose ; stems low, filiform, 

 somewhat flexuous, simple ; rough on the angles which are form- 

 ed by the equally wide grooves between, and furrows on the cari- 

 nas ; on each side of the grooves a single series of stomata ; val- 

 lecular air-cavities large, no carinal ones, no central cavity ; sheaths 

 somewhat turbinate, variegated with black, consisting of three, 

 rarely four, 4-carinate leaves ; the points persistent, ovate, cuspi- 

 date, membranaceous, whitish. 



Hab. Arctic America, (Beck's Botany,) Newfoundland, (Herb. 

 Willd.,) Canada, (Michx.,) Northern States, (Carey, Oakes, and 

 others.) Lately discovered also in Arctic Europe. 



This is the smallest of all the known species, with very rarely 

 more than three teeth in the sheaths, but always double the num- 

 ber of angles on the stem. Three of the grooves between these 

 angles correspond with the leaves and are without stomata ; the 

 three alternating ones correspond with the commissure of the 

 leaves, and have each two ranges of stomata. 



tt Ranges of stomata consisting each of two or more rows. 



E. giganteum, Linn, and others, of South America, belongs 

 here. Several species undoubtedly have been confounded under 

 this name, which are all nearly related to E. robusiam, but are 

 well distinguished by having two or three rows of stomata in each 

 range. No North American or European species, so far as known, 

 belongs to this section. 



