MOSSES WITH A HAND-LENS 



195 



Perigonial. See bracts. 



Peristome, the fringe surrounding the mouth of the capsule 

 upon removing the lid. This 

 fringe may consist of a single 

 row of processes, known as teeth, 

 as in Fig. 7, or of a double row as 

 in Fig. 27. In the latter case the 

 entire fringe is still the peris tome, 

 but the term is also applied in a 

 particular sense to the outer row; 

 the outer row is often spoken of 

 as the exostome (b), and the 

 inner as the endostome (c)- The 

 inner row consists of as many 

 projections as the outer, but al- 

 ternating with them; these are 

 known as processes or segments 

 (c). Between the segments there 

 are often one or more slender 

 hair-like processes known as 

 cilia. (Fig. 27, d; Fig. n, c.) 

 FIG. 27. Moss peristomes, viewed with a 



compound microscope, are among the most beautiful of natural 

 objects. They are not composed of cells (except in the Polytri- 

 chaceae and a few other small fam- 

 ilies), but of thickened cell-walls. 



Pinnate, having numerous equi- 

 distant spreading branches on each 

 side like a feather. (Fig. 28.) 



Pleurocarpous, having the sporo- 

 phyte lateral on a short lateral special 

 branch. (Fig. 29.) Pleurocarpous 

 mosses can usually be recognized by 

 the creeping habit. 



Plicate, folded in pleats or furrows ; e. g., 

 leaves of Camptothecium. (Fig. 30.) 

 Plicae, folds of a plicate leaf. 

 Plumose, feathery. 



Pluriscriate, many ranked ; i. e., as applied to leaves arranged 

 in several rows along the stem. 



Polygamous, with antheridia and archegonia disposed in 



