350 WOODSIESE. PART n. 



ferns vary much with regard to the dimensions and 

 elevation of their stem. The caudex of Cibotium Ba- 



rometz is covered with long 

 tawny hair ; each has its own 

 peculiarity. The species of 

 Dicksoniese belong principally 

 to the tropics and southern 

 isles. The ferns of this group 

 have globose sori, which are 

 submarginal, seated at the tip 

 of a vein or veinlet. The in- 

 sorusandcup-shap^dT- dusium is lateral, persistent, 



slum of Deparia prolifera. an( J bivalved ; the lower Valve 



is formed by the true indusium, the upper by the altered 

 tooth of the frond folded back. In Dennstsedtia the in- 

 dusium is cup-shaped, and curiously deflexed ; while in 

 Deparia, another section of the group, the cup-shaped 

 indusium containing the sorus is extrorse marginal, as 

 shown in fig. 60. 



The group Peranemese, or Woodsiese, is represented 

 in the British Flora by two species of Woodsia, which 

 are amongst the rarest and most curious of our ferns, 

 and inhabit the crevices in our highest mountain tops. 

 Their tufts of fronds are not more than two or three 

 inches high, sometimes less, and the fronds themselves 

 are lanceolate, and pinnate ; in Woodsia ilvensis they 

 have oblong and usually opposite deeply lobed pinnse, 

 whose under-surface is clothed more or less with jointed 

 hairs and long attenuated scales. The sori in both 

 species are circular, and situated at the extremity of 

 the lateral veins. When young they are covered with 

 an indusium, which opens at the centre, and forms a 

 cup round the sori ; afterwards it is divided into nu- 

 merous jointed and usually incurved threads. 



The Davalliese are mostly tropical and subtropical 

 ferns. Their sori are submarginal, placed upon the tip 



