94 THE BOOK OF NATURE STUDY 



From their habit it is obvious that both plants are but poorly 

 adapted, as compared with other ferns, for successful competition 

 with other plants living in the same habitats. This is especially 

 the case with adderstongue, whose erect leaves are so scantily 

 produced, but this plant sends up its leaves in early spring, so 

 as to catch the light before there are too many competing plants, 

 and part of the food they make is stored in the fleshy stem and 

 roots ; in May or June the spores ripen, and soon after the leaf 

 dies down. But if the plant is carefully dug up, with plenty of 

 the soil about its roots, and put in a cool greenhouse, it will remain 

 fresh and green until late in autumn, showing that the early 

 death of the leaves is due largely to the keen competition for 

 light and air which takes place in the adderstongue's habitat in 

 summer, when larger plants have grown up around and over it. 



Horsetails and Clubmosses (Lycopods), are allied to ferns, 

 but belong to distinct groups. Each is comparatively poorly 

 represented on the earth nowadays, the modern horsetails and 

 clubmosses being the puny descendants of once great families of 

 large and stately plants which flourished during the Coal Period, 

 and have left their remains in still more ancient rocks. The 

 ancestors of the horsetails (the Calamites) and of the club- 

 mosses (the Lepidodendrons and Sigillarias) were tall trees 

 forming a large part of the Coal Period forests, and their remains 

 can be seen in almost every museum of natural history. 



The Field Horsetail (Equisetum arvense), the commonest of 

 our British horsetails, will serve as a type for study. It grows 

 chiefly in damp sandy soil, in meadows, by roadsides, on railway 

 embankments, margins of woods, and in cultivated fields and 

 neglected gardens. Like bracken, it has a stem which burrows 

 deeply in the soil, but the parts which come above ground are 

 in this case shoots and not merely leaves. In summer the plant 

 shows green jointed shoots, each consisting of a cylindrical stem 

 bearing at intervals circles of outgrowths which are often branched 

 again. At the upper end of each joint there is a collar-like 

 sheath with pointed teeth on its edge. This sheath consists of a 

 series of leaves joined by their bases. The branches grow out 

 of the lower part of the collar a rather peculiar mode of origin 

 for branches. If you look at the nodes of a youngish plant you 



