MALE PERN. 343 



end blindly this forked venation is characteristic of 

 Fern leaves. The leaf -stalk bears scattered scale-hairs, 

 which are also sometimes present on the main veins of the 

 leaflets. 



(c) In summer the mature leaf bears, on its lower 

 side, the sori projections arranged in two rows on each of 

 the lobes of the leaflets ; the sori are at first light green, 

 but later turn brown. Each sorus consists of a collection 

 of small stalked bodies, the sporangia or spore-cases, 

 covered by a white kidney-shaped membrane or indusium. 

 Pick off the indusium with your forceps, and note that it 

 has a stalk arising in the midst of the sporangia ; on 

 removing the sporangia themselves, note that they spring 

 from a small cushion (placenta) seated on one of the 

 veins. 



(d) The yonng leaves which will unfold next spring 

 and the next again, and are covered with the brown scale- 

 hairs lying within the expanded leaves, at the growing 

 apex of the stem ; a rosette of leaves is formed each year, 

 but each leaf takes two years to develop. Each young leaf 

 is rolled up lengthwise like a watch-spring (circinate 

 vernation, characteristic of Fern leaves), owing to the 

 greater growth of the lower (and outer) side of the leaf ; 

 each leaflet is rolled up in the same way. Carefully remove 

 the brown scales from successively younger leaves ; in the 

 first year only the stalk is (as a rule) developed, the blade 

 being formed later. 



(e) The buds, which occur at the base of some of the 

 leaves ; and the hard wiry roots, also arising from the bases 

 of the leaves close to their junction with the stem. The 

 roots are (except at the tips) dark brown or almost black, 

 and much branched; the branching is monopodial, the 

 branches arising in acropetal succession. 



482. General Anatomy of Rhizome. With a knife 

 or razor, pare down the leaf -bases on the older part of the 

 shoot, for about three inches, also remove the roots ; then 

 cut off this portion and set it to steep in dilute (about 

 10 per cent.) hydrochloric acid (for 483). 



