40 EQUISETACEAE. VOL. I. 



3. Equisetum sylvaticum L. Wood Horsetail. Bottle-brush. Fig. 91. 



Eqnisetuin sylvaticum L. Sp. PI. 1061. 1/53. 



Stems annual, provided with scattered stomata, the 

 fertile appearing in early spring before the sterile, at first 

 simple, at length much branched and resembling the sterile, 

 only its naked apex withering. Stems usually 12-furrowed, 

 producing verticillate compound branches, the branchlets 

 curved downward ; sheaths loose, cylindric or campanulate, 

 those of the stem with 8-14 bluntish teeth, those of the 

 branches with 4 or 5 teeth, those of the branchlets with 3 

 divergent teeth ; central cavity nearly one-half the diameter 

 of the stem ; branches and branchlets solid. 



In moist sandy woods and thickets, Newfoundland and 

 Greenland to Alaska, south to Virginia and Iowa. Also in 

 Europe and Asia. May. 



4. Equisetum palustre L. Marsh Horsetail. Fig. 92. 



Equisetum palustre L. Sp. PI. 1061. 1753. 



Stems annual, slender, all alike, io'-iS' long, very 

 deeply 5-9-grooved, the grooves separated by narrow 

 roughish wing-like ridges, the central canal very small; 

 sheaths rather loose, bearing about 8 subulate-lanceolate 

 whitish-margined teeth ; branches simple, few in the 

 whorls, 4~7-angled, always hollow, barely sulcate, more 

 abundant below than above, their sheaths mostly 

 5-toothed ; spike rather long; stomata abundant in the 

 furrows. 



In wet places, Nova Scotia to Alaska, Connecticut, 

 western New York, Illinois and Arizona. Also in Europe 

 and Asia. July-Aug. Marsh-weed, Paddock-or Snake- 

 pipes ; Cat-whistles. 



5. Equisetum littorale Kuehl. Shore Horsetail. Fig. 93. 



Equisetum littorale Kuehl. Beitr. Pflanz. Russ. 

 Reichs, 4: 91. 1845. 



Stems annual, very slender, all alike, S'-i8' 

 high, slightly roughened, 6-ig-grooved, the ridges 

 rounded, the central canal one-half to two-thirds 

 the diameter; sheaths sensibly dilated above, the 

 uppermost inversely campanulate, their teeth her- 

 baceous, membranous at the margins, narrow, 

 lanceolate ; branches of two kinds, simple, some 

 4-angled and hollow, some 3-angled and solid, 

 the first joint shorter or a trifle longer than the 

 sheath of the stem ; spike short with abortive 

 spores, these commonly with no elaters. 



On sandy river and lake shores, New Brunswick 

 and Ontario to New Jersey and Pennsylvania, west 

 to British Columbia. Also in Europe. Supposed to 

 be a hybrid. Aug.-Sept. 



