240 



MORPHOLOG V. 



The Horned Liverworts.* 



601. The horned liverworts take their name from the shape of the spo- 

 rogonium. This is long, slender, rylindrical, pointed, and very slightly 

 curved, suggesting the shape of a minute horn. Anthoceros is one of the 

 most common and widely distributed species. The plant grows on damp 

 soil or on mud. 



Anthoceros. 



602. The gametophyte. — The gametophyte is thalloid. It is thin, flat- 

 tened, green, irregularl}- riblmn-shapefl and branched. It lies on the soil 



and is more or less crisped or 

 wavy, or curled, the edges nearly 

 plane, or somewhat irregular, 

 and with minute lobes, or 

 notches, especialh' near the 

 growing end. The general form 

 and branching can be seen in 

 fig. 270. Where the plants are 

 much crowded the thallus is more 

 irregular, and often possesses nu- 

 merous small lateral branches in 

 addition to the main lobes. 

 Upon the under siclc are the 

 slenrler rhizoids, which attach 

 to the soil. With a hand lens 

 there can be seen also upon the 

 under side small dark, rounded 

 and thickened spots, where an 

 alga (nostoc) is located. 



Sexual Organs of 

 Anthoceros. 



502. The sexual organs of an- 

 thoceros differ considerably from 

 those of the other liverworts 



Anthoceros gracilis. A, 



several gameto- 

 phvtes. on which sp.jrangia have developed, 

 B, an enlarged sporogoniuni, showing its studied. In the first place they 

 elongated character and dehiscence bv two , i • .i , .■ ' 



valves, leaving e,xp..sed the slender columella are immersed m tile true tissue 

 on the surface of which are the spores, C. D. „f ^Y^^ thallus, i.e., they do tiot 

 R, r, elaters ot various lonns, O. sijores, 

 (.^ftcr Scliiftner,) project above the surface, 



503, Antheridia, — The antheridium arises from an internal cell of the 



thallus, a cell just below the upper surface. This cell develops usually a 



* May be used as an alternate study for marchantia. 



