326 



MUSCINE^. 



which still resembles that class ; the lowest forms of all the groups exhibit many 

 resemblances which are wanting in the most highly developed. We have therefore four 

 diverging series. 



I. The Sphagnacese^ include only the single genus Sphagnum. When the spores 

 germinate in water, a branched protonema is developed, on which the leaf-buds imme- 

 diately appear laterally (Fig. 237, C). On a solid sub-stratum, on the other hand, the 

 short protonema forms first of all a branching flat pro-embryo (Fig. 238), on which 

 (as in Tetraphis) the leaf-buds appear. The leafy stems produce root-hairs only in the 

 young state, the abundant protonema of true Mosses is entirely wanting. The stem, 

 as it increases in strength, produces laterally, by the side of every fourth leaf, a branch, 

 which, even at the very earliest period, is again much divided ; tufts of branches arranged 

 regularly thus arise which form a compact mass at the summit of the stem, but lower 



Fig. 238. — Sphaipinrn actttifoHinii ; the flat pro-enibryo /r with a young 

 leafy stem 711 (after Schimper, x about 20). 



Fig. 237. — Sphagnmn aciUifolhatt ; A a large 

 spore, seen froin the apex ; B a small spore ; C a 

 protonema n it' resulting from the spore s; pr rudi- 

 ments of young plants (after Schimper). 



down are more divergent. The separate branches develope in different ways; one is 

 produced each year beneath the summit after the ripening of the fruit, and developes 

 in a similar manner to the primary stem, growing up along with the prolongation of 

 the latter, so that each year a false dichotomy takes place on the stem. These inno- 

 vations afterwards become separated by the slow decay of the plant advancing from 

 below, and constitute independent plants. Some of the branches of each tuft, however, 

 turn downwards, become long, slender, and finely pointed, and are closely applied to the 

 primary stem, forming a dense envelope around it ; while other branches of each 

 tuft turn outwards and upwards. The leaves spring from the stem and the branches 

 from a broad base, and are usually arranged with a 



^ W. P. Schimper, Versuch einer Entwickelungsgeschichte der Torfmoose. Stuttgart 1S58 (with 

 many beautiful plates). 



