714 



SYSTEMATIC BOTANY. 



flask-sliaped body [jig. 803), which after fertilization developes 

 an urn-shaped sporangium {figs. 804-806) with a central colu- 

 mella {fig. 810) ; the space between which and the walls of the 

 sporangium being occupied by spores, withoiit any elaters among 

 them. The sjjorangiitm is commonly placed on a stalk {seta) 

 {figs. 804, t, and 805, p), or occasionally sessile {fig. 1092), 

 and at first is covered by a hood {calyptra) {figs. 805 and 



806, c), beneath which is a kind of lid {operculum) {figs. 807, 

 0, and 808). The sporangium usually opens when ripe in a 

 transverse manner from the separation of the operculum {figs. 



807, 0, and 808) ; or sometimes by splitting vertically into four 

 equal valves, which are connected at the summit by the persistent 

 operculum {fig. 1092, a) ; or rarely it dehisces irregularly. At 

 the dehiscence of the sporangium, its mouth {stoma) is seen to 

 be either fringed by one {aploperistomous) or two rows {diplo- 

 peristomous) of teeth {'peristome) {fig. 807, p), or naked {ggmno- 

 sto)nous) {fig. 808). 



Division of the Order, and Examples of the Genera. — This order 

 is usually divided into two sub-orders, which are frequently re- 

 garded as separate orders. The princi- 

 pal distinctive characters of the two 

 are as follows: — 



Sub-Order 1. BryacecB or Bryea. — Urn- 

 Mosses. — Sporangium dehiscing trans- 

 versely by the separation of the oper- 

 culum, or irregularly. Examples : — 

 Bryimi, Polytrichum, Sphagnum. The 

 genus Sphagnum is by Henfrey made 

 to constitute a distinct order, under 

 the name of Sphagnacese ; the species 

 are principally distinguished from the 

 Bryaceae in habit, and by the curious 

 structure of their leaves. 



Sub-Order 2. AndrceacecB or AndrmecB. 

 - — Split-Mosses. — Sporangium split- 

 ting vertically into 4 valves which are 

 connected at the summit {fig. 1092). 

 Examples : — Andrssa, Acroschisma. 

 These are the only genera in this sub- 

 order. 



Distribution and Numbers. — They are 

 generally diffused over the globe, but 

 most abundantly in temperate climates. 



Fig. 1092. A portion of An- 

 drcea ritpcstris, much mag- 

 nified. Tlie stem is erect, 

 with numerous small iiu- 

 liricated leaves, and a ter- 

 minal sporanKium, which 

 is de.-<timte of a seta. a. 

 Sporangium after deh 



cence. showing the 4 equal There are about 1.250 species, 

 valvcsof whicli It IS com- ^/'Vi.^i • i. 



posed connected at the Properties ana Uses. — 01 little import- 



opercuium^ Tife va^^^^^^^^ either in a medical or economic 



seen to have dehisced ver- point of view. Some species possess 

 ticaiiy. After Hooker. astringent and diuretic properties, but 



