THE VASCULAR CRYPTOGAMS 



79 



FIG. 38. Equisetum arvense. 1 and 2, general view of plant, showing 

 underground rhizome, bearing roots, with fertile and sterile aerial 

 stems. 1, Fertile stems ; a, ripe cone. 2, much branched sterile 

 stem ; a (on rhizome), tubers. 3, single peltate scale from cone, 

 showing sporangia. 4, similar scale from below ; sporangia dehiscing. 

 5, young spore, with elaters not yet expanded. 6, mature spore in 

 damp condition ; elaters curled up. 7, the same in dry condition ; 

 elaters expanded. Figs. 1 and 2 reduced ; Figs. 3 and 4 magnified 

 slightly ; Figs. 5, 6, and 7 very highly magnified. (After "Wossidlo, 

 from Strasburger.) 



