CAPSULES 21 



The capsule is usually borne above the leafy plant on 

 a fruit-stalk, or seta (Plate IV, Fig. i) of varying length. 

 In some cases the capsule is partly hidden by the sur- 

 rounding leaves when the seta is very short. If the 

 seta comes from the apex of the stem or of a well- 

 developed branch, the fruit is spoken of as terminal " 

 and the moss is called "acrocarpous " ; if the seta comes 

 from the side of the stem or is on a very short lateral 

 branch, the fruit is spoken of as '' lateral " and the moss 

 is called ''pleurocarpous." The color of the seta is 

 usually yellowish or reddish. 



An erect capsule is upright like the seta; when not 

 erect, it may be inclined, horizontal, or drooping. For 

 the various shapes of capsules and their characteristic 

 positions see Plate IV, Figs. 3-16. 



There are interesting parts of the capsule — the 

 operculum and the peristome — that with the calyptra 

 serve as a protection while the fruit is immature. (See 

 Plate IV, Figs. 1,2.) 



The calyptra is like a hood covering the young cap- 

 sule. It usually falls off before the spores are ripe, but 

 if it remains on until the capsule fills out, it is often 

 pushed upwards and finally covers only the beak of the 

 operculum. In a few cases the calyptra is covered with 

 hairs. (See Ulota, p. 119, and Polytrichum, p. 162.) It 

 may be hood-shaped (cucullate) (Plate IV, Fig. 17) or 

 like a beaked cap (mitrate) (Plate IV, Fig. 18). 



Nearly all capsules open by means of a lid, or oper- 

 culum. It is the upper portion of the capsule that be- 



