Equisetum (HORSETAIL) 



A. Classification: 



Division IV. Calamophyta. 

 Class II. Equisetineae. 

 Order. Equisetales. 

 Family. Equisetaceae. 

 Genus. Equisetum. 

 Species, (e.g.) arvense. 



B. Habitat: 



i. The field horsetail (E. arvense), is common along 

 railway embankments, roadsides and fields. It 

 apparently prefers north-facing slopes, and has a 

 great tendency to become weedy. 



C. Naked-eye Characters: 

 i. The Stem. 



(a) Using herbarium specimens or alcoholic material, 

 if fresh material is not available, observe the 

 underground stem (rhizome), and the upright 

 aerial branches. 



(b) Of the latter, observe two kinds; (i) non-green, 

 unbranched, bearing only scale leaves, and 

 terminating in a prominent strobilus or cone; 

 (2) green and branched, bearing leaves, but 

 no cone. 



(c) Which kind of aerial branch appears first above 

 ground in the spring ? What advantage may this 

 possess for the species? 



(d) Explain the physiological significance of the 

 green color of the non-reproductive branches. 



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