228 VEGETABLE ORGANOGRAPHY. 



several botanists have given to the leaves of Ferns the 

 vague name of Fronds. 



Whatever term may be preferred for these peduncu- 

 late-leaves, or foliaceous-peduncles, we shall observe 

 that their position upon the stem is similar to that of 

 leaves, and that they may in like manner be divided into 

 petioles and limbs furnished with nerves and parenchyma. 

 Although the limb is often very much divided, there is 

 never any articulation between its parts, and it must 

 always be compared with simple leaves. 



In general, those fronds which do not bear the fruc- 

 tification, as those of Osmunda, are large and foliaceous 

 throughout their whole extent. This appearance is met 

 with in all those which bear a moderate number of fruc- 

 tifying organs, for example, Polypodium, Pteris, Sec. 

 But when the number of these organs is very great, then 

 the foliaceous limb diminishes and seems to disappear, 

 being covered or hidden by the development of fruits ; 

 this is seen clearly in several species of Acrostichum; 

 and following analogies which leave but little doubt, we 

 come to understand that Ferns said to be spiked, as 

 Ophioglossum, only owe this appearance to a more com- 

 plete and constant abortion of the foliaceous limb. Let 

 us also remark that in the cases where the organs of 

 fructification are moderately dispersed upon the fronds, 

 these latter still being able to perform the physiological 

 functions of true leaves, may be all fertile, as Polypodium, 

 Pteris, Sec. ; whilst, if the fructifying organs are accu- 

 mulated in great numbers upon certain fronds, so as to 

 deprive them of all the functions of leaves, it then hap- 

 pens that there are upon the same stem other fronds, 

 said to be sterile, which perfectly enjoy the functions of 

 leaves ; this is seen in Osmunda, Ophioglossum, Sec. The 

 vernation of the fronds of all or nearly all Ferns is cir- 

 cinate, or in other terms, they are rolled up from the 



