'4 



I 



i^' 



1907] STOKEY— ROOTS OF LYCOPODIUM PITHYOIDES 63 



11. Strasburgee, E., Einige Bemerkungen iiber die Lycopodiaceen. Bot. 



Zeit. 31:113- 1873. 



12. Underwood, L. M. and Lloyd, F. E., The species of Lycopodium of the 



I American tropics. Bull. Torr. Bot. Club 33:109-110. 1906. 



EXPLANATION OF PLATES V AND VI 



All the figures were drawn with the aid of an Abbe camera lucida and reduced 

 one-half in reproduction. Abbreviations are as follows: x^ xylera; px, pro- 

 toxylem; ph, phloern; e, endodermis; pCy peri cycle; c, cortex; sc, sclerenchyma; 

 plj plerome; pb^ periblem; d^ dermatogen; ca^ calyptrogen; pr, primordium. 



PLATE V 



Fig. 2. Cross-section ofstemshowingstele surrounded by "inner roots." X8. 

 Fig. 3. Cross-section of stem with primordium of root. X8. 

 Fig. 4. Primordium of root at its origin from stele of stem. X i6o. 

 Fig. 5. Longitudinal section of root tip. Xi6o. 



Figs. 6-8. Dermatogen of root showing development of trichomes. X375. 

 Fig. g. Surface view of trichoblast cell which has divided to form two tri- 

 chomes. • X375. 



Fig. 10. Longitudinal section through "inner root" at origin. X8o. 

 Fig. it. Diagram of a root-tip of an " inner root/' showing dichotomy. 



PLATE VI 



Fig. 12. Cross-section of '4nner root." X180. 



Fig. 13. Cross-section of "inner root" at origin. Xi8o. 



Fig. 14. Cross-section of stele of stem at origin of "inner root" (xylem 

 strands shaded). X6o. 



Fig. 15. Cross-section of stele of stem showing root almost separated from 

 stele. X60. 



xyl 



root leaves the stele of the stem. X 180. 



Fig. 17, Cross-section of stele of root just above the place where the root 



X leaves the stem. X180. 



Figs. 18-20. Cross-section of stele of root showing division of xylem during 

 forking of the root. X 180. 



Fig. 21. Cross-section of external root. X25. 



