PTBRIDOPHYTA— PILICIN^ 



141 



The sporangia, situated as described above, are usually 

 quite independent of each other, not being arranged in sori. 

 They are often embedded in the tissue of the sporophyll and 

 open when ripe by valves or slits. Each contains numerous 

 spores. 



The gametophyte is best known in Ophioglossiim pedun- 

 culosum and Botrychium Lunaria. In the former it is a 

 tuberous body growing underground and devoid of chloroplastids. 

 From it springs a cylindrical gametophore, which grows up 

 through the earth and becomes green. It bears antheridia and 

 archegonia. In the latter it is again tuberous and subterranean ; 

 it has root hairs, and bears antheridia and archegonia, the latter 

 being chiefly on its lower and the former on its upper surface. 



Maeattiaceae. 



The stem of the sporophyte, as in the last case, is generally 

 a rhizome, which is sometimes branched, and bears numerous 



Fig. 899. 



Fig. 899. Synaugia, s, of A, Angiopteris, E, Marattia ; c, section of synan- 

 gium of E. After Sachs. 



leaves. The latter resemble those of the true ferns, from which 

 they differ by bearing well-marked stipules. The roots branch 

 considerably, the branching being lateral. 



The histology of the stem recalls that of the true ferns, the 

 arrangement of the vascular tissue being polystelic, and the 

 bundles of the steles concentric. There is more variety in regard 



