SERIES II. 

 I CRYPTOGAMOUS or FLOWERLESS PLANTS. 



Vegetables destitute of proper flowers (i. e. having no 

 stamens nor pistils), and producing instead of seeds minute 

 one-celled germinating bodies called spores, in which there 

 is no embryo or rudimentary plantlet. 



Class III. ACROGENS. 



Cryptogamous plants with a distinct axis or stem, grow- 

 ing from the apex, and commonly not with later increase 

 in diameter, usually furnished with distinct leaves ; repro- 

 duction by antheridia and archegonia, sometimes also by 

 gemmation. 



Subclass I. VASCULAR ACROGENS, or PTERI- 

 DOPHYTES.^ 



Stems containing woody fi])re and vessels (especially scalari- 

 form or spiral ducts). Antheridia or archegonia, or both, 

 formed on a minute prothallus which is developed from the 

 spore on germination, the archegonium containing a nucleus, 

 which after fertilization becomes an oospore and at length 

 grows into the conspicuous spore-bearing plant. 



Order 130. EQUISETACE^. (Horsetail Family.) 



r 



Rush-like, oflen branching plants, with jointed and mostly hollow stems 

 from running rootstocks, having sheaths at the joints, and, ichen fertile, 

 terminated hy the conical or spike-like fructification composed of shield- 

 shaped stalked scales hearing the spore-cases beneath. — A single genus. 



1 The orders of this Subclass have been elaborated anew for this edition by 

 Prof. Daniel C. Eaton of Yale University. 



