Explanatory Notes on Mosses 



499 



plumule, and no radicle, and it is therefore thought best to 

 deny the term "seed" to these spores, although they are 

 sexually produced. 



(13) The name given to the first filamentous growth from 

 moss spores is " protonema." It resembles the mycelium or 

 spawn of a fungus, but unlike it is always green. A yet more 

 close resemblance is perhaps to a conferva (an alga). 



(14) After a certain duration in its leafless and stemless 

 form, the protonema develops stems and leaves, and these in 

 turn produce flowers and fruit. 



(15) Mosses stand between seaweeds and ferns, but show 

 remarkable differences from both. 



(16) The Liverworts are classed with mosses or as very 

 close allies. They are sometimes called " leafless mosses," 

 having instead of leaves a broad flattened stalk. Their urns, 

 or sporangia, open by side valves, and not, as do the mosses, 

 by a mouth at the top of the urn. 



(17) The term Urn is singularly well adapted as the familiar 

 equivalent for many forms of sporangium. The sporangia of 

 mosses differ in pattern as tea-urns do, and show as many 

 varieties of form ; they have mouths like urns and many have 

 lids, many also have in their centres a columella, equivalent 

 to the heater of the urn. Unfortunately tea-urns have so 

 nearly gone out of use that their names will soon convey no 

 clear meaning, and we shall have to fall back on the original 

 but less cheerfully associated utensils of that name. 



