346 ASPIDIEJE. PART n. 



distinguished by its naked globular sori, which in this 

 species are regularly disposed in a line on each side of 

 the mid vein, half way between it and the margin of the 

 leaf. When young, they are of a yellow or bright 

 orange colour, which changes to brown when they are 

 ripe. The rhizome, which branches in all directions, is 

 at first clothed with a skin densely covered with yellow- 

 ish brown membranaceous lanceolate scales, which at 

 length fall or become obliterated, leaving the surface 

 nearly smooth. The Polypodium vulgare has many 

 varieties, several of which are well marked, especially 

 that called cambricum, which is twice pinnatifid. The 

 plant is common in temperate climates. 



The Aspidiese form an extensive and widely distributed 

 group, embracing several of our common British species. 

 One of these is the genus Lastrea, which has, for the 

 most part, lanceolate fronds, bipinnate or tripinnate 

 in division, with linear lanceolate, and usually pinnatifid 

 pinnae. The sori are nearly circular, seated upon the back 

 of the veins, and covered by a reniform indusium, which 

 is attached by its sinus. In Lastrea Filix-mas (fig. 57), 

 one of our commonest ferns, the fronds 

 spring up in a rather spreading mass, 

 from the extremity of a long scaly 

 caudex, and often present a vase-like tuft 

 hollow in the centre. The rachis, leafy 

 through a third or a fourth of its 

 length, is more or less clothed with thin 

 membranaceous scales, of a pale often 

 Fig. 57. pinnule of brownish-golden hue, a peculiarity com- 



Lastrea Filix-mas * -r 



with sori. mon to the 'other Lastrese. Lastrea 



Thelypteris, the Marsh Fern, however, has them not, and 

 differs also from most of its congeners in having its sori 

 subinarginal. Its rhizome has a widely creeping habit 

 of growth. The Lastrea semula has globular glands, 

 sessile over the whole under-surface of the fronds, which 



