CHAPTER XXVI. 



BRYOPHYTA, MOSS PLANTS AND PTERIDOPHYTA, FERN 



PLANTS. 



N 



THE BRYOPHYTA are in some sense a transition group between 



the cellular plants below and the well developed vascular plants 

 above. A plant called Marchantia polymorpba is a good repre- 

 sentative of a portion of this group. It is found in damp shady 

 places, growing on the rocks or on moist ground. It consists 

 of flat leaf-like stems, producing fine silky hairs from the lower 

 surface which serve to attach it to its resting place, and they 

 probably absorb nourishment as well, acting as true roots. The 

 dark green upper surface is covered with minute diamond-shaped 

 markings. 



The reproductive organs occur on separate plants as disk- 

 crowned stems about an inch high. The antheridia or male ele- 

 ments have a scalloped disk, while the archegonia or female ele- 

 ments have the disk cut into finger-like rays. After fertilization 

 a sexual spore, called an oospore, is formed in the archegonium, 

 from which a sporogonium is developed. In the sporogonium 

 asexual spores are formed from which new plants grow. On the 

 upper surface of the plant little cups or cupules occur which con- 

 tain bright green scale-like bodies called gemmse. The gemmae 

 grow into new plants. 



In studying this plant notice carefully the points already men- 

 tioned, note the difference in color between the upper and lower 

 sides of the plant, note the mode of branching, the indented 

 apex, the median line or midrib. Note also the pores on the 

 upper surface. Remove some of the gemma? and placing them 

 on a white surface, study their form. Examine carefully the 

 orchegomal and antheridial branches, and compare them with 

 (200) 



