242 MORPHOLOG Y. 



what and are romewhat irregular and sometimes divide or branch. They 

 are supposed to represent rudimentary elaters. The cells in the other tiers 

 are actual mother-cells, and each one forms four spores. 



509. The sporophyte of anthoceros represents the highest type found in 

 the liverworts. The spongy green parenchyma forming the wall, with the 

 stomata in the epidermal layer, fits this tissue for the process of photosyn- 

 thesis, so that this part of the sporophyte functions as the green leaf of the 

 seed plants. It has been suggested by some that if the rhizoids on the 

 nourishing foot could only extend outside and anchor in the soil, the sporo- 

 phyte of anthoceros could live an independent existence. But we see that 

 it stops short of that. 



Classification of the Liverworts. 



CLASS HEPATIC.E. 



510. Order Marchantiales.* There are two families represented in 

 the United States. 



Family Ricciaceae, including Riccia and Ricciocarpus. 

 Family Marchantiaceae, including Marchantia, Fegatella (=Cono- 

 cephalus), Fimbriaria, Targionia, etc. 



511. Order Jungermanniales.* There are two subdivisions of this order. 

 The AnacrogyncB include chiefly thalloid forms with continued apical 

 growth, the archegonia back of the apical cell. Examples: Blasia, Aneura, 

 Pellia, etc. 



The Acrogyna include chiefly foliose forms, the archegonia arising from 

 the apical cell and in such cases interrupting apical growth. Examples: 

 Cephalozia, Frullania, Bazzania, Jungermannia, Ptilidium, Porella, etc. 



CLASS ANTHOCEROTES 



512. The Anthocerotes have formerly been placed with the Hepaticaa 

 as an order. But because of their wide divergence from the other liver- 

 worts in the development of the sexual organs, and especially in the struc- 

 ture of the sporophyte, they are now by some separated as a distinct class. 

 There is one order. 



Order Anthocerotales* This includes one family (Anthocerotacese) 

 with Anthoceros and Notothylas in Europe and North America, and Den- 

 droceros in the tropics. The latter is epiphytic. 



* As subclass in Engler and Prantl. 



