400 BOTANY 



alternate, often deeply divided or compound leaves. Sporangia either 

 on the under side of the sporoph ylls, united in sori or free, or enclosed 

 in special segments of the leaves. 



Order 1. Filices. — Ferns, in the narrower sense. Homosporous. 

 Order 2. Hydropterideae. — Water-Ferns. Heterosporous. 



2. Equisetinae. — Horse-tails, stem simple or verticillately branched, 

 with whorled, scale-like leaves forming a united sheath at each node. 

 Sporophylls shield-shaped, bearing the sporangia on the under side, and 

 aggregated into a cone at the apex of each fertile shoot. 



Order 3. Equisetaceae. — Horse-tails. Homosporous. 



3. Lycopodinae. — Club Mosses. Stems elongated, dichotomously 

 branched, either forked or forming a sympodhim, with leaves, in 

 many cases greatly reduced, or shortened and tuberous with awl- 

 shaped leaves. Sporangia arising singly in the form of firm-walled 

 capsules either from the stem, in the leaf -axils, or from the leaf -base. 



Order 4. Lycopodiaceae. — Club Mosses. Homosporous. 

 Order 5. Selaginellaceae. — Heterosporous. 



There are also various fossil groups, some of which are included 

 in the above divisions, while some form independent orders. 



Class I 



Filieinae (Ferns) 



Order 1. Filices 



The Filices (True Ferns) constitute the larger part of the Vascular 

 Cryptogams. They comprise a large number of genera with numerous 

 species, being widely distributed in all parts of the world. They 

 attain their highest development in the tropics. The Tree-Ferns 

 (Cyathea, Alsophila, etc.), which include the largest representatives of 

 the order, occur in tropical countries, and characterise the special 

 family of the Cyatheaceae. The stem of a Tree-Fern is woody and 

 unbranched ; it bears at the apex a rosette of pinnately compound 

 leaves or fronds, which are produced in succession from the terminal 

 bud, and leave, when dead, a large leaf scar on the trunk. The stem 

 resembling that of a Palm in habit, it is attached to the soil by means 

 of numerous adventitious roots. 



The majority of Ferns, however, are herbaceous, and possess a 

 creeping rhizome, terminating usually in a rosette of pinnate or deeply 

 divided leaves. Such a habit and growth are illustrated by the common 

 Fern Aspidium filix mas, the rhizome of which is officinal. 



When young, the leaves (fronds) of this Fern are coiled at the tips 

 (Fig. 332, 1, a), a peculiarity common to the Ferns as a whole, and to the 



