PEAOTICAL BOTANY. 



PART II. 



BRYOPHYTA. 



A. MUSCI. 



POLYTRICHUM COMMUNE, L. 



A. GENERAL EXTERNAL CHARACTERS. 

 I. Observe in well-grown specimens of this Moss 

 taken in spring or early summer 



1. The erect stem, 1 which may attain a considerable 

 length, branching but rarely : 



2. The leaves, 1 of relatively small size, and simple 

 form ; their arrangement is on a complicated plan 

 (see below) : at the base of the stem note 



3. A dense mat of rhizoids of brown colour. 



At the apex of some specimens will be found merely 

 a bud, composed of young leaves of the vegetative 

 type ; other specimens will bear at their apex 



4. Perigonia, or perichaetia ; cup-like rosettes of 

 leaves, which assume a bright reddish or orange colour, 



1 Though the terms "stem" and "leaf " are used here, it must be 

 distinctly borne in mind that the members thus named, being parts of 



the oophore generation are not homologous with, but at most 



only analogous to the stem and leaf in vascular plants, which are 



parts of the sporophore generation. 



B 



