PRINCIPAL GROUPS OF PLANTS. 



93 



cristata) and maiden hair spleenwort (Asplenium Trichomanes), 

 to plants several feet high, as in the several species of Osmunda 

 (Fig. 54), ostrich fern (Fig. 55), etc. This group is chiefly 



FIG. 56. A, transverse section of stipe of Dryopteris marginalis: E, epidermis; H, 

 hypodermis of collenchymatous cells; P, parenchyma containing starch; V, fibrovascular 

 bundle; S, sieve; T, trachea?; N, endodermis surrounding each bundle. B, transverse sec- 

 tion of stipe of Osmunda Claytoniana: H, hypodermis of lignified sclerenchymatous fibres; 

 N, endodermis surrounding a large central fibrovascular bundle; Tn, tannin cells. 



characterized by the underground or prostrate stems, known as 

 rhizomes, the part of the plant that is seen above ground being 

 the leaf. 



