MUSCINEJG. 



431 



buds (a, 6), each of which grows up into a new leafy stem, forming a 

 tufted group of plants, which after a time fructify again by anthendia and 

 archef/onia. 



MTJSCI. MOSSES. 



Fig. 500. 



Diagnosis. Sexual Generation: Plants of a diffused or creep- 

 ing habit, terrestrial or aquatic, with imbricated leaves arranged in 

 from two to four rows, and branching in a monopodial manner. 

 The stems are slender and con- 

 tain no true vascular tissue. 

 A true root is absent, but its 

 functions are performed by 

 root-hairs. The sexual genera- 

 tion arises as a lateral shoot 

 from a protonema produced by 

 the asexual spore on germina- 

 tion. It bears the antheridia 

 and archegouia the former 



stalked and the latter sessile on 

 a narrow base. The Asexual 



Generation or sporogonium 



arises from the embryonic cell 



of the archegonium after fer- 

 tilization by an antherozoid. 



Its first stage of development OrganizationofMo83es: _ A ;^^ 



is passed in the calyptra, 



which, on being ruptured at 



the vaginula, is carried up on 



the apex, where the capsule 



which produces the spores is 



formed (figs. 497, 498, 500). Within the capsule is a sterile mass 



of tissue called the columella. The epidermis of the capsule splits 



to permit the escape of the spores. Illustrative Suborders : Brya- 



cece, Sphagnacece, Andrceacece. 



In the BBYACEJE the leaves are small and scale-like and usually spirally 

 arranged. The plants are of a csespitose or diffused creeping habit. The 

 antheridia and archegonia are produced either in terminal buds or in the 

 axils of leaves. From the archegonium, the outer part of which is a flask- 

 shaped sac, arises the sporogonium, w r hich in its growth tears away the 

 wall of the archegonium, leaving the base as a kind of collar (vaamula^ 

 fig. 500, c), and carrying away the upper part, which becomes more deve- 

 loped as a cap or hood (calyptra, d) this more or less encloses the urn- 

 shaped capsule (6) until it is mature (fig. 500, A) ; the stalk of the sporo- 

 gonium is called the seta. When the calyptra falls off it exposes the 

 capsule, which in most cases has a deciduous lid (operculwn,f) ; when 



natural size ; b, its capsule, with operculum in 

 situ,, and calyptra (d) detached ; c, the base of 

 the seta, with the vaginule; e, capsule, with 

 peristome, and, e', a section of the same, show- 

 ing the columella;/, the operculum of e; h, 

 teeth of the peristome, from the mouth of e; i, 

 spores, on the same scale of amplification as h. 



