432 SYSTEMATIC BOTANY. 



the lid falls off, the border of the mouth of the capsule is found either 

 naked or furnished with a single or double fringe of teeth (peristome, e, h) ; 

 and a circular piece, called the annulus, sometimes separates from the end 

 of the columella in this place. The number of teeth in the peristome is 

 either four or some multiple of that number. In the capsule of Mosses is 

 to be found a colurnella or stalk-like mass of tissue running up the centre 

 (e r ). In the Phasceee an operculum is absent, and the spores escape on the 

 decay of the capsule. It differs slightly in its general structure from othe*r 

 Bryacece. Illustrative Genera : Phascum, L. j Grimmia, Ehr. ; Tetraphis, 

 Hedw. 5 Splachnum, L. ; Dicranum, Hedw. ; Trichostomum, Hedw. ; En- 

 calypta, Hedw. ; Bryum, L. ; Bartramia, Hedw. ; Funaria, Hedw. ; Poly- 

 tj'ichum, L. ; Hypnum, L. ; Foidinalis, L. 



SPHAGNACEJE consist of the species of one genus, Sphagnum. The plants 

 are aquatic, and are commonly known as "Bog-mosses." They are of a pecu- 

 liar yellowish-green aspect, with imbricate (o-rowed) leaves and fasciculate 

 branches, the lower of which are long and denexed. This genus differs 

 very much from the Bryacece in habit and in the structure of its leaves. 

 The chlorophyll-containing cells of the leaves are slender and elongated ; 

 in the interstices are large empty cells, the walls of which are strengthened 

 by a spiral fibre. This structure causes the whitish or yellowish-green 

 colour peculiar to them and to a few similarly organized Mosses. The 

 antheridia are globose stalked bodies and resemble those of Hepaticce 

 more than those of Mosses. The sporogonium possesses a short turbinate 

 seta, and a capsule which dehisces by an operculum, and is destitute of a 

 peristome ; the columella is short and does not reach the apex. A pecu- 

 liarity of the asexual generation is the existence of sporogonia bearing 

 spores of a smaller size than the ordinary large spores. This Order is 

 remarkable for the share it takes in covering bogs and gradually furnishing 

 material for peat, the lower parts of the stems gradually dying away below 

 while the summit ascends ; the descending lower branches of the fascicles 

 bind the whole into a compact mass. They abound in cold and temperate 

 climates in boggy places, furnishing an article of food to animals, and even 

 to man in northern regions. 



ANDRJEACEJE are csespitose Mosses with erect stems and imbricate 

 leaves, and are natives of mountains and polar latitudes. The sporogonium 

 has constantly a terminal position on the stems of the sexual plants and 

 is destitute of a seta. The capsule is sessile on the receptacle where the 

 vagimda arises and bursts vertically into four valves, which remain con- 

 nected at the apex. A columella is present. In Acrodiisma, a genus 

 from the Antarctic regions, the valves separate only halfway down, as in 

 the Phascece (Bryacece), in which Archidium, like ^Andrcea, does not ele- 

 vate the capsule on a seta, but carries up the calyptra simply by the ex- 

 pansion of the capsule. In the 4-valved dehiscence it agrees with the 

 Jungcrmanniacece (Hepaticce). Illustrative Genera : Andrcea, Ehr., and 

 Acrochisma, Hook. til. 



