I 



416 A TEXTBOOK OF THEORETICAL BOTANY 



Mniiim hormim is relatively simple in structure and has been selected in 

 preference to the well-known type Fiinaria hygrometrica, which it resembles, 

 owing to the fact that in most parts of the country it is more easily obtained 

 in the quantities necessary for class material. The description of Mniiim, 

 however, covers in all essential features the characteristics of Funaria. 

 Polytrichutn commune is a rather specialized Moss showing considerably more 

 elaborate structure than that of Mniiim. 



Mnium hornum 



This common Moss is found growing in large tufts in woods, especially 

 Beech woods, and on shady banks. It is 2 to 3 in. in height, bright green 





Fig. 398. — Mnium hormim. Leafy plant bearing 

 sporogonia. Natural size. 



in colour, and consists of a brownish-green stem covered with prominent 

 leaves which are developed spirally (Figs. 398 and 399). The reproductive 

 organs are produced on separate plants at the apices of the branches and 

 are surrounded by an involucre of larger leaves. They appear during May 

 and June, and the female plants frequently bear archegonia and old capsules 

 at the same time. The male flowers are yellowish-red, and more conspicuous 

 than the female, as the involucral leaves stand out in a circle round the cluster 

 of antheridia. 



The stem tissues show a certain amount of differentiation, and it is 

 possible to distinguish a central axial cylinder, about one-fifth of the 

 diameter of the stem, composed of narrow, much-elongated, thin-walled 



