FRUCTIFICATION. 1 1 



or twice pinnate ; but if the pinnae are only deeply iobed 

 they, like the frond when similarly divided, are said to be 

 piiinatifid. 



When the fronds are thrice pinnate, they are called tri- 

 pinnate; and in all other more intricate forms, they are 

 called decompound; but this seldom occurs in our native 

 kinds, the nearest approach to it being in very vigorous 

 plants of the common Bracken, and in some of the Lastreas, 

 when very largely developed. 



The young fronds of the Ferns before being developed are 

 arranged in a very curious manner, the rachis being rolled 

 inwards volutely from the point to the base. In the com- 

 pound sorts the divisions are each again rolled up in a 

 similar way. This arrangement is what is called circinate. 

 All the British species, with two exceptions, are folded up 

 in this way, so that their development consists of an un- 

 rolling of the parts of the frond. The exceptions mentioned, 

 are the Moon wort and the Adder's-tongue, in both of which 

 the fronds in the undeveloped state are folded straight. 



The substance of the fronds is traversed by veins variously 

 arranged ; in some species forming straight, nearly parallel 

 lines, in others joined together like network. The manner 

 in which the veins are disposed is called the venation, and 

 the nature of this venation affords useful data in the division 

 of the Ferns into family groups. It is from some part of 

 these veins, determinate in position, that the clusters of 

 fructification proceed, the part to which they are attached 

 being called the receptacle. 



A correct appreciation of the nature and position of the 

 receptacle with reference to the veins, is of considerable im- 

 portance in the study of the family groups and the indivi- 

 dual kinds. In some, though few of the native kinds, it is 

 projected beyond the margin, and the little cases of seeds 

 are collected around the extremity of the vein, which pro- 

 jects outwards from the edge of the leaf. More commonly, 

 however, the veins stop within the margins, and the seed- 

 cases grow in round or elongated clusters, sometimes placed 

 at their ends, sometimes along their sides, appearing on the 

 lower surface of the fronds. 



No flowers are produced, but the plants bear, generally, 

 great abundance of seed-like bodies, which are technically 

 called spores, and are contained in little hollow cases of very 

 singular construction. Collectively, these cases and their 

 contents are called the fructification ; and the cases them- 

 selves are attached in the different species to certain deter- 



