226 



PTERIDOPHYTA. 



Class 3. Lycopodinee (Club-Mosses), 



The characteristics of this class have been given on page 205v 

 It consists of two sub-classes, one embracing isosporous, the other 

 heterosporous forms. 



Sub-Class 1. Lycopodieae (ISOSPOROUS Lycopodina3). 



One kind of spore. Prothallium large, partly green. Leaves- 

 without ligule. 



PIG.. 229. Lycopodium annotinum: A em- FIG. 230. Lycopodium clavatum? 



byro (nat. size), with prothallium (pr), one portion of astern, bearing cones (a) ; 



embryo is broken off; JB the prothallium s, a spore; 7i sporangium in the axil 



(slightly magnified) ; C section through the of a leaf, s. 

 prothallium and embryo in the direction a-b 

 sf A, and vertically in the plane of the paper. 



Order 1. Lycopodiaceae. The PROTHALLIUM is DOW known in 

 nearly all the species ; it is always more or less tubercular, and 

 bears both antheridia and archegonia. 



In L. annotinum the prothallium is a relatively large mass of cells, without 

 chlorophyll, and subterranean, in which the antheridia and archegonia are 

 embedded (Fig. 229). In the widely distributed tropical species, L. cernuum,. 



