OF EQUISETALES 



149 



verticil : these variations in number of the sporangiophores would be 

 difficult to harmonise with any reference to "leaf-segments," as ordinarily 

 understood elsewhere; and their disposition suggests the idea of chorisis 

 of the sporangiophore similar to that seen frequently in the stamens of 

 Angiospermic flowers. 



FIG. 78. 



Forked sporophyll of Spheno- 

 phyllum majits, bearing spor- 

 angiophore. (After Kidston.) 



FIG. 80. 



of 



Calamostachys. Diagram 

 cone in radial section. ax = a.x\s, 

 which bears successive verticils of 

 bracts (br), and peltate sporangio- 

 phores (sp). sm = sporangia borne 

 on the sporangiophores. As the 

 bracts are alternate with one 

 another their upturned tips are 

 only shown in every alternate 

 verticil. (After Scott.) 



FIG. 79. 



Equisetum maximum, Link. A, the 

 upper part of a fertile axis, with the lower 

 half of the strobilus. Natural size. b = the 

 leaf-sheath. = annulus. jr = stalks of spor- 

 angiophores cut off. y = transverse section of 

 axis. 2>=sporangioprrores in various posi- 

 tions, slightly enlarged. st = stalk. sg-= 

 sporangia. s = enlarged distal end. (After 

 Sachs.) 



In the Equiseta and Calamarians, spore-bearing bodies of outline not 

 unlike those of Psilotaceae are attached directly to the axis itself, and bear 

 the pendent sporangia (Fig. 79). They show sometimes almost constant, 

 but frequently inconstant, numerical and local relation to the whorls of 



