MOSSES 41 



shaped fertilising organs discharging its con- 

 tents. The rosette-like flowers of the Hair-moss 

 (Polytrichum) family, already described at page 

 34, will provide convenient illustrations of the 

 same thing; they should be examined in early 

 summer, and, of course, fresh specimens must be 

 used. 



There is one feature in connection with these 

 reproductive organs that calls for special mention, 

 as it often constitutes a very important item in 

 the diagnosis of any particular species ; this is 

 the relative positions of the two kinds on the 

 plant. In some instances the fertilising organs 

 alone are formed on one plant, and the fruit- 

 bearing organs on an entirely separate one in 

 which case the moss is said to be dioicous; in 

 others they both grow on the same plant, but 

 separated the one from the other, and the moss 

 is then spoken of as autoicous (or monoicous). 

 Again, sometimes the two kinds are not only 

 borne on the same plant, but are actually mixed 

 together, and the moss is then known as synoicous-, 

 while if both fertilising and fruit-bearing organs 

 are to be found in the same flower, but in 

 distinct groups, as occasionally happens, we have 

 a paroicous moss. Plate II. figs. 4 (Pottia 

 truncatula), 5 (Fissidens taxifolius), 10 (Tortula 

 murali-s), and 13 ( Grimmia pulvinata) are instances 

 of autoicous plants, while those given at figs. 1 

 (EurhyncMum pumilum), 2 (Mnium punctatum) , 12 



