THE HORSETAIL FAMILY. 487 



Barren stems. 

 Stem white, with numerous long branches, three to five) 1. Great White-stem- 



feet high J ^ed Horsetail. 



Stem green, one to two feet high. 



Branches scarcely any. Growing in ponds 4. Pond Horsetail. 



Branches numerous. 

 Branches drooping and subdi^'ided, so as to form 



cupolas round the stem. (Fig. 212) 3. Sylvan Horsetail. 



Branches spreading and simple, or nearly so. 



Branches very few in a whorl 5. Marsh Horsetail. 



Branches ten or twelve. (Fig. 213) 2. Field Horsetail. 



Fertile stems. 

 No branches. 



a. Growing in water, intermingled with barren stems, 



and forming dense forests, like rushes 4. Pond Horsetail. 



b. Growing in marshes or on land, and appearing and 



withering before the barren stems are produced. 

 Sheaths at least an inch long, completely covering ] 1. Great White-stem- 



the intemodes ) med Horsetail. 



Sheaths less than an inch long, and far apart ; 



large and coarse; their teeth about ten. 



No rudiments of green branches. (Fig. 213) 2. Field Horsetail. 



c. Growing in swamps or on land. Sheaths delicate, 



with six to eight scarious lobes. Young green 

 branches appearing below them, and developed 



before the spikes have decayed 3. Sylvan Horsetail. 



Stems more or less branched. 

 Branches pendulous, forming little cupolas round the 



stem. (Fig. 212) 3. S^xvan Horsetail. 



Branches not pendulous. 



Scores of the stem and teeth of the sheaths about 



fifteen or twenty 4. Pond Horsetail. 



Scores and teeth rarely moi-e than eight 5. Marsh Horsetail. 



HABITATS AND LOCALITIES. 

 1. Great White-stemmed Horsetail — {JEguiseium Telmateia.) 

 In marshy and swampy places, where shaded by trees, common 

 everywhere. Fertile stems in May, rather rare. Cotterill. Marple 

 Wood. Barren ones, July — September. 



E. B. xxix. 2022 (as Equisetum fluvidtile). 

 The tall white stems, which are often four or five feet high, and handsome 

 green spreading branches, are a gi'eat ornaTiient to our wet doughs and marshy 

 places as autumn approaches, and, like the water-lilies, seem Indian rather than 

 Enghsh. A spike is sometimes found upon a branched stem. 



