354 EQUISETACEM. [chap. 



aquatic or terrestrial, with a short unbranched stock, and 

 tufted linear or subulate sheathing leaves, in the bases of 

 which the sporanges are embedded. The mode of repro- 

 duction in Lycopodium has not yet been traced throughout, 

 but in Selaginella, in which tlie lower sporanges contain 

 macrospores, and the upper microspores, a narrow scarcely 

 protruding prothallus is developed upon the former, bearing 

 archegonia upon its surface, which are fertilised by anthero- 

 zoids set free by the microspores. 



3. Natural Order, Equisetacece. — The Horsetail Family. 



Herbs with hollow jointed stems, with or without slender 

 vvhorled jointed branches. Fructification, a terminal spike, 

 consisting of numerous closely-packed peltate scales bearing 



Fig. 237. Unbranched fertile and branched barren fronds of Horsetail. 



sporanges of one kind around their margins, parallel with 

 their short stalks. Outer coat of the spores splitting into 

 elastic attached hygroscopic filaments (elaters). Developing 

 a prothallus as in Ferns. 



