VI 
PREFACE. 
article upon the Physiology of Ferns, in the Reliquary, Vol. 
I. p. 35—37. 
This elementary notice of the Fern tribe, as being a group 
of Bud-seeded plants, leads to the explanation of the terms 
employed in this and in other works on Ferns, in describing 
the individual species. The true fibrous roots of a Fern, are 
distinct, generally, from the more or less underground, and 
often prostrate and creeping stem, or rhizome, which is, 
however, called caudex, when, being erect, it tends to be- 
come, as in Tree Ferns, an upright trunk : from this the 
stalk of the fronds arises, which, up to the leafy part or 
lamina, is called the stipes, and above the leaf, or division 
of the leaf, it becomes the rachis. This central stalk is 
sometimes branched, and that mostly by forking : and from 
it, the costce or mid veins branch into the flat substance of 
the leaf, and, when branched again, are called costules or vein- 
lets. If the veins do not branch, they are described as simple ; 
when they branch and so end, they are said to be forked 
and free : if, however, they unite at their extremities and 
form a network, they are said to anastomose, and the spaces 
thus enclosed by the united veins are termed areoles. 
The whole, stipes, rachis, and lamina, is called a Frond; 
if undivided, it is considered simple ; if it divides, and the 
divisions are stalked, each stalked division is called a pinna. 
If a pinna be again divided, and the divisions stalked, such 
secondary divisions are called pinnules. These stalked 
divisions of the main leaf are often multiplied two or three 
times and more. But if divisions of the main leaf occur, which 
are not stalked, such a frond is said to be only pinnatifid. 
Each mass of fruit on the frond is called a sorus or heap, 
and usually consists of many membranous capsules, thecae 
or sporangia, with or without an elastic ring. The ring is, 
doubtless, designed to aid both in the bursting of the 
capsule, and in the dispersion of its contents. If a frond of 
the common Hart’s-Tongue be gathered on an open day in 
winter, and the under surface is suddenly exposed to the 
