6 
We walk invisible. 
Nay, by my faith, I think you are more beholden 
To the night than to fern seed for your walking invisible.” 
Shakspeare, Henry 4, Act 2, Scene 1. 
There is also a great difference between the veins on the 
leaflets of Ferns and those on the leaves of the great orders 
of flowering plants. There generally is a mid-vein, from 
which issue veins on either side, that are either undivided 
or divide into two, three, or four lines, with the fructification 
on one or more of these. Many of the Ferns found in the 
coal formations are named according to the division and 
direction of the veins. The fronds are rarely undivided, as 
the Hartstongue. Plate II, fig. 17. AVhat, indeed, consti- 
tutes the chief beauty and elegance of this part of the vege- 
table world, is the peculiarly chaste and striking manner in 
which the various parts of a frond are cut and severed. Not 
the finest tool of the most skilful mechanic could perform 
such exquisite workmanship. No rich colour, as in the rose 
and camelia, no sweet perfume, as in the violet : it is the 
matchless distribution of the various parts, that is so attrac- 
tive and ornamental. Some Ferns have the fronds deeply 
divided, but not to the mid-rib or rachis as the common 
Polypody, Plate I, fig. 3. Others are divided to the rachis 
and have distinct leaflets on each side, as the Maidenhair 
Spleenwort, Plate II, fig. 12. These are said to be pinnate 
and the frond is called a pinna. If on either side of the 
rachis, we have many pinnae, as Plate II, fig. 11, the Fern is 
said to be bipinnate ; and, if instead of mere leaflets on such 
a pinna, there are some little pinnae or branchlets, as Plate 
I, fig. 8, * then it is said to be tripinnate. If as in Plate I, 
fig. 6, the branches are deeply divided, but not to the mid-rib, 
then the frond is said to be nearly bipinnate. The elegance 
is also increased by little incisions or cuts on the edges of 
the leaflets, some resembling those of a saw (serrate), some 
bluntly notched, and others more rounded. A few have 
little bristles here and there, as in the Prickly Fern, Plate I, 
fig. 4. The shape of the leaflet should be attended to, as 
this gives a character to the plant. They are either egg- 
shaped, as the Adder’s-tongue, or lance-shaped, as in the 
Black-stalked Spleenwort, or oblong as the Mountain Fern, 
* Particularly notice the lowest pinnae. 
