LIVERWORTS AND MOSSES. 



49 



themselves branch, there is formed a bipinnate or even tri- 

 pinnate system, as in figure 42, ^. 



59. Protonema. — In its early stages the vegetative body 

 of the leafy liverworts and the mosses is either a flat thallus, 

 similar to the mature form of the 

 thallose liverworts, or a branching 

 filamentous body, called the pro- 

 tonema, almost identical with the 

 form of the branched filamentous 

 algae. Upon this protonema the 

 leafy shoot arises as a lateral bud, 

 which soon outstrips it in growth 

 and develops leaves. The pro- 

 tonema may live for some months, 

 but generally perishes after having 

 produced a few leafy plants. 



60. Sporophyte. — The non- 

 sexual phase in the liverworts and 

 mosses has almost no vegetative 

 functions. It consists at maturity 

 of a yellowish or brown spherical or 

 cylindrical case (fig. 46), which is 

 sessile or raised upon a short or 

 long stalk and contains (a few or) 

 hundreds or thousands of repro- 

 ductive cells called spores. The 

 pointed or swollen base of this 

 stalk is called the " foot," and is embedded in the gameto- 

 phyte (/", fig. 47) to absorb food from it. 



61. Nutrition. — The surface of the young sporophyte, 

 when large and well developed, as it is in the higher liver- 

 worts and mosses, is green. To a limited extent, therefore, 

 it is able to make food ; but not sufficient for its needs, for 

 these are great on account of its rapid growth and the amount 



Fig. 45.— Axis of a moss iOrtho- 

 trickum) showing sympodial 

 brandling. S^, .S^, iS, .s*, suc- 

 cessive clusteis of sex-organs, 

 produced at apex, whicli check 

 the growth of axis. Beneath 

 each a lateral growing point 

 develops, producing successively 

 the branches b^, 3'-', b^. Magni- 

 fied 10 diam. — After Brucli & 

 Schimper. 



