248 MORPHOLOG Y. 



materials are passed from the gameli)pl]"\-te to the sporogonium. The upper 

 part continues to grow, and finally the upper end differentiates into the mature 

 capsule. 



523, Protonema of the moss.— When the spores of a moss germitiate they 

 form a thread-like body, -with cliloropliyll. This thread becomes branched, 

 and sometimes quite extended (angles of these threa<is are formed. This is 

 called the protonema, that isy/r.f/ thread. The older threads become finally 

 brown, while the later r.nes are green. From this protonema at certain 

 points buds appear which divide by close oblique walls. From tliese buds 

 the leafy stem of the moss plant grows. Threads similar to these protonemal 

 threads now grow out from the leafy stem, to form the rhizoids. These 

 supply the moss plant with nutriment, and n(jw the protonema usually dies, 

 though in some few species it persists for long periods. 



Classification of the Mosses. 



CLASS MUSCINE^ (MUSCI). 



524. Order Sphagnales.* — This order includes the peat mosses. There 

 is but one family (Sphagnaceie) and but a single genus (Sphagnum). The 

 peat mosses are widely distributed <)\'er the globe, chiefly occurring in 

 moors, or "bogs," usuallv low ground around the shores of lakes, ]ionds, or 

 along streams, but ttiey often occur (jn wet dripping rocks in cool shady 

 places. Small ponds are sometimes filled in bv their growth. As the 

 sphagnum growing in such an abundance of water onlv partiallv decavs, 

 "ground" is built up rather rapidly, and the sphagnum remains are known 

 as "peat." This "ground "-building pecuharity of sphagnum sometimes 

 enables the plant (often in conjunction yvith others) to fill in ponds com- 

 pletely. (See Atoll Moor, Chapter LV.) 



The gametophyte of sphagnum, like that of all the mosses, is dimorphic, 

 but the first part (or protonema) which develops from the spores is thalloid, 

 and therefore more like the thallose liverworts. The leafy axis (or gameto- 

 phore) which develops from the thalloid form is very characteristic (see 

 Chapter lA'). 



The archegonia are born<" on the free end of the main axis, while the 

 anlheriflia are borne on short branches which are brightly colored, red, 

 \-ello\y, etc. The sporo[)h\'te (sporogonium) is globose and ]H)ssesses a 

 broad foot anchored in the end of a naked prolongation (^f the end of the 

 leafy gametophore. This naked prolongation of the gametopbore l(toks 

 like the stalk of the sporogonium, but a study of its coniuTtion with the 

 s[)orogonium sliows llial it is part of (he gamctoj)h\'te, whii h is only devel- 

 oped after the fertilization of the egg in the archegoniuni. In the sporogo- 

 nium there is a short columella, and the archesporium is in the form 01 nn 

 inverted < m|"). 



* As subclass in h'.ngler and Prantl. 



