Series II. CRYPTOGAMOUS or FLOWERLESS PLANTS. 



Plants never bearing true flowers, tliat is, having no stamens nor pistils, and pro- 

 ducing instead of seeds minute homogeneous bodies, called spores, in which there is 

 nothing of the nature of an embryo. 



Class III. ACROGENOUS PLANTS or ACROGENS. 



Cryptogamous plants with a distinct axis or stem, growing from the apex, and 

 with usually no subsequent increase in diameter, and furnished for the most part 

 with distinct leaves ; reproduction by means of antheridia and archegonia, sometLines 

 also by gemmation. 



Subclass I. VASCULAR ACROGENS. (By Prof. Daniel C. Eaton.) 



Stems containing both woody and vascular tissue. Antheridia or archegonia, or 

 both, formed on a prothallus which is developed from the spore on germination, 

 and upon which the conspicuous but non-sexual plant is produced. 



Division I. ISOSPOROUS VASCULAR ACROGENS. 



Plant producing but one kind of spore ; antheridia and archegonia both produced 

 on a prothallus. 



Order CXX. EQUISETACE^. 



Rush-like, often branching plants, with jointed and almost always hollow stems 

 rising from subterranean rootstocks, the sterile leaves represented by a toothed 

 sheath at the joints, and the fertile ones forming a short spike at the end of the 

 stem or branches. 



Thei-e is but one genus. 



1, EQUISETUM, Linn. Horse-Taiu ScotirjNG-Rusii. 



Perennial plants with extensively creeping rootstocks. Stems simple or branched, 



furrowed longitudinally and many -jointed, provided with a central cavity, as wi'll 



as with cavities opposite the furrows and an intermediate series of minute hollows 



opposite the ridges. The joints have closed ends, and are crowned with a toothed 



