CRYPTOGAMS 



435 



and form large tussocks saturated with water. The upper extremities of the 

 stems continue their growth from year to year, while the lower portions die 

 away and become eventually converted into peat. 

 Of the numerous lateral branches arising from each 

 of the shoots, some grow upwards and form the 

 apical tufts or heads at the summits of the stems ; 

 others, which are more elongated and flagcllifonn 

 in shape, turn downwards and envelop the lower 

 portions of the stem (Fig. 389 A). Every year one 

 branch below the apex develops as strongly as the 

 mother shoot, so that the stem thus becomes falsely 

 bifurcated. By the gradual death of the stem from 

 below upwards the daughter shoots become separ- 

 ated from it, and form independent plants. Special 

 branches of the tufted heads are distinguishable by 

 .their different structure and colour ; on these the 

 sexual organs are produced. The male branches 

 give rise, near the leaves, to spherical stalked 

 antheridia, which open at the apices by means of 

 valves ; these bend back and let free the spirally 

 twisted spermatozoids (Fig. 389 E, F). The arche- 

 gonia are borne at the tips of the female branches. 



FIG. 393. Schistostega osiwindacea. 

 A, Sterile ; B, fertile plant, (x 5.) 



The sporogouium develops a 

 short stalk with an expanded foot (B, 0), but remains for a time enclosed by the 



FIG. 394. Hypnum purum. (Nat. size.) 



FIG. 395. AInlum undulatum. Orthotropous 

 shoot terminating in a male receptacle sur- 

 rounded by involucral leaves. The lateral 

 shoots are plagiotropous. (After GOEEEL.) 



archegonial wall or calyptra. Upon the rupture of the archegonium, the calyptra 

 persists as in the Hepaticae at the base of the sporogonium. The capsule is spherical 

 and has a dome-shaped columella, which in turn is overarched by a hemispherical 



