DEVELOPMENT OF PLANTS 



335 



of over thirty-five feet. Species of Equisetum are of common 

 occurrence in nearly all countries, living in shallow ponds, 

 swamps, and marshes or drier soils. 



At first sight they show little suggestion of fern relationship 

 (Fig. 232) and impress one as being singularly out of harmony 



FIG. 232. A common. horsetail, Equisetum arvense: a, the green branch- 

 ing plant that lives through the summer /, scale leaves; r, rhizome or under- 

 ground stem with tuberous storage organs, b, early spring shoot that bears 

 a spike or strobilus of modified spore-bearing leaves, sp. This stem is of a 

 light brown color and withers after the spores are shed. H. O. Hanson. 



with our common plants, as though they were indeed relics of 

 a past age. The large leaves, which were so characteristic of 

 the Filicales, are reduced to minute papery scales in this order 



