LASTEEA MONTANA. 133 



appears in abundance, and from tliat period all the fronds are 

 fertile. In the form of the frond there is little or no variation ; 

 it is elongate - lanceolate, and regularly pinnate : pinnse acute 

 at the apex, and gradually diminishing from about two-thirds 

 of its length to the very base, the lower pinn£e being remark- 

 ably short, and nearly triangular in form : this attenuation of 

 the frond towards the base is an excellent diagnostic (see figure 

 b, page 129), and is of itself sufficient to distinguish the present 

 from any other British fern. There is but a very small portion of 

 stipes below the pinnje, and this is nearly hidden by pale brown 

 scales. The pinnse are linear and acute at the apex, rather 

 distant, deeply pinnatifid, and attached to the main rachis only 

 by their midrib : a separate pinna is represented of the natu- 

 ral size at a, page 129. The pinnules are rounded and slightly 

 crenate : over the entire under surface are scattered small, yel- 

 lowish, glandular globules, which are adhesive to the touch, 

 and emit a powerful but not very agreeable odour : it is proba- 

 bly in consequence of this property that the species was origi- 

 nally named Polypodium fragrans by Linneus. 



The veins in the pinnules of Lastrea montana are alternate, 

 and are either simple or branched : in the latter case both veins 

 are fruitful, as in Hemestheum Thelypteris. Sometimes the 

 veins or branches are again divided just before their termina- 

 tion, and then each of the subdivisions is usually fruitful : all 

 the veins and branches cease just before the 

 margin of the pinnule : the clusters of cap- 

 sules are circular, and are placed very near 

 the extremity of each vein, so as form a 

 nearly marginal series. In some instances, y^^ V^®/ 



but by no means generally, a small, torn, 

 white involucre is to be seen near the centre 

 of each cluster of capsules, as represented 

 in the margin. This involucre is said to be 

 reniform, a character I have never been able 

 to detect : in general the masses are perfectly naked, and even 

 before the frond has unrolled this absence of an involucre is 

 equally manifest ; a circumstance worthy of notice, as showing 

 that its frequent absence is a character, and not the result of 

 age or accident. 



