280 



yCALY SPLEENWOET. 



The radicles of the scaly spleenwort are short, but possess a 

 remarkable power of penetrating mortar, however hard it may 

 be ; they also find their way into rocks which appear to present 

 the most compact surface. Still, from the luxuriance of some 

 plants sent me by Mr. Thwaites, it would appear that this spe- 

 cies thrives much more vigorously in the rich vegetable mould 

 which has been accumulating during centuries in the deeper 

 fissures : here the radicles are longer, but still appear short as 

 compared with those of other rock-loving species. The caudex 

 is tufted, brown and scaly. The young fronds make their 

 appearance in May, and before unfolding are nearly white : 

 they arrive at maturity in autumn, and continue green and vi- 

 gorous throughout the winter : they are always fertile. The 

 stipes is short, and beset more or less thickly with pointed 

 scales : the form of the frond is linear, slightly attenuated be- 

 low, and deeply pinnatifid ; the segments are short, rounded, 

 and sometimes crenate or lobed ; their position as regards the 

 stipes is rather oblique ; their entire under surface is densely 

 clothed with brown, pointed, imbricated scales, which, when 

 examined under the microscope, are found to be very beauti- 

 fully reticulated. While the frond 

 retains its circinate or undeveloped 

 form, these scales are nearly white. 

 The midvein of each pinna is waved 

 but distinct ; the lateral veins are 

 few in number, alternate, and irre- 

 gularly branched ; the branches oc- 

 casionally anastomose before their 

 termination, as represented by the 

 -"^l -a^f^g^^^^^^;;;^ ^:^ figure in the margin : the anterior 



branch of each bears an elongate 

 cluster of capsules ; these are situated about midway between 

 the midrib and the margin of the pinna ; the points of their at- 

 tachment are indicated in the figure : the first anterior lateral 

 vein usually bears two clusters of capsules, one on each of its 

 princi]pal branches : the capsules are attached to that side of 

 the vein which is nearest the median line of the pinnre, and not 



