PRINCIPAL GROUPS OF PLANTS. 



93 



cristata} and maiden hair spleenwort (Asplenium Trichowianes}, 

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

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



--E 



B 



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, tracheae; 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. 



