570 A TEXTBOOK OF THEORETICAL BOTANY 



Sclerenchyma surrounds the bundle, but no endodermis can be recognized. 

 The leaf traces are given off from the protoxylems at the outer margins of the 

 xylem plates in the stem and make no leaf gap in the stele as they leave it. 



The lamina shows no apical growth, as do Fern leaves. The highly 

 cuticularized epidermis contains no chlorophyll, but has stomata, usually 

 on both sides of the leaf. The mesophyll tissue is very spongy and 

 undifferentiated. 



Anatomy of the Root 



The roots of the mature plant are all adventitious and are borne ventrally 

 on the stem, arising in acropetal succession, but without any definite spacing 



Fig. 579. — Lycopodium clavaturti. Transverse section of 

 an old root showing dichotomy. Note the similarity 

 of the stelar anatomy to that of the stem. 



or relationship to other organs. They are produced endogenously from the 

 pericycle and they branch dichotomously (Fig. 579). No lateral roots are 

 formed, but root hairs arise in pairs, as the result of oblique divisions in the 

 surface cells. There is an apical meristem and a root cap is developed, as 

 in Angiosperms (see p. 794). 



The anatomy of the mature root differs very little from that of the stem, 

 though the stele is smaller and simpler. There are from seven to ten 

 protoxylems, and the corresponding metaxylem masses often unite in the 

 centre, presenting a stellate form, with the phloems between the rays. 

 Smaller roots may be only diarch. The close similarity of anatomical 

 structure between the stem and the root is very interesting morphologically, 

 as it indicates the unity of the axis in all its parts, whether leaf-bearing or not. 

 This is clearly shown in Lycopodium because the leaves are too small to 

 affect the stem anatomy to any great extent. The alteration of stem structure 

 seen in Ferns and higher plants, where it differs markedly from that of the 



