THE GENUS EQUISETUM, 



1 89 



Explanation of Plates. 



PLATE 20. 



Fig. 1. Young archegonium of Equisetum hiemale. 



Fig. 2. Older archegonium of E. hiemale. 



Fig. :>. < >l<ler archegonium of E. hiemale. 



Fig. 4. Nearly ripe archegonium of E. hiemale. 



Fig. 5. Nearly ripe archegonium of E. arvense. 



Fig. 6. Young embryo of E. hiemale. 



Fig. 7. Older embryo of E. hiemale. 



Fig. 8. Still further advanced embryo of W. hiemale. 



Fig. 9. Young sporophyte of E. hiemale. 



Fig. 10. Older sporophyte of the same species. 



Fig. 11. Advanced sporophyte of E. hiemale. 



Fig. 12. Young sporophyte of E. limosurn. 



Fig. 13. Older sporophyte of the same species. 



Fig. 14. Diagram showing the relation of the leaf-trace to the nodal wood in E. hiemale. n. iv. nodal wood ; e. endo. 

 dermis; p. t. protoxylein ; I. t. leaf-trace. 



Fig. 15. Diagram of the node of Archaeocalamiles. I. leaf-traces; b. branches. 

 Fig. 10. Diagram of the node of Equisetum. I. leaf-traces ; b. branches. 



Fig. 17. Surface of a Calamite showing the scars of leaves, branches, and root. For explanation see page 181. 



PLATE 27. 



Fig. 1. Stele of Selaginella laevigata showing the origin of a branch. X25. 

 Fig. 2. Stele of the same species below the point of origin of a branch. X25. 

 Fig. 3. Stele of Lepidodendron harcourtii at the point of origin of a branch. X25. See page 101. 

 Fig. 4. Tangential view of the bundles at the node of a Calamite, copied from Williamson. See page 103. 

 Fig. 5. Tangential view of the bundles at the node of a Calamite, copied from another of Williamson's figures. See 

 page 103. 



Fig. 0. Tangential view of the bundles at the node of a Calamite, copied from a figure of Williamson and Scott. See 

 page 104. 



PLATE 28. 



Fig. 1. Tangential view of the bundles at the node of a Calamite, copied from Renault. See page 105. (In this figure 

 there are leaf traces,/, only at alternate strands, a state of affairs not uncommon in the Calamites). 

 Fig. 2. Transverse section of a young trifascicular stem of Equisetum limosum. X200. 

 Fig. 3. Transverse section of the stem of E. hiemale in the nodal region, a. branch ; b. a root. X25. 

 Fig. 4. Nodal organ of E. hiemale. X200. 



Fig. 6. Transverse section through the node of E. silvaticum. a. nodal organs ; b. roots ; c. a branch ; d. leaf-traces ; 

 X25. 



Fig. 0. Node of E. arvense. c. branches ; d. leaf-traces. X25. 



