MUSCI. 



?>11 



The same length of time is required by Philonotis, and by some species of Bryum 

 and some of Polytrichum which blossom in May and June \ 



Mosses may be distributed naturally into four parallel orders : — 



1. Sphagnaceae, 



2. Andreaeaceae, 



3. Phascaceae, 



4. Bryaceae (True Mosses). 



Of these the first includes a single genus, the second and third only a few ; the fourth all 

 the remaining extremely numerous genera. The first three groups recall, in many 

 respects, the Hepaticae ; even the series of true Mosses commences with some genera 

 which still resemble 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 Sphagnaceae^ 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. 258, C). 

 On a solid substratum, on the other 

 hand, the short protonema forms first 

 of all a branching flat protonemal 

 expansion (Fig. 259), on which (as 

 in Tetr aphis) the leaf-buds appear. 

 The leafy stems produce root-hairs 

 only in the young state. The abun- 

 dant protonema of true Mosses is 

 entirely wanting. The stem, as it 

 increases in strength, produces later- 

 ally, 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 

 down are more distant from each 

 other. The separate branches de- 

 velope in diff'erent ways ; one is pro- 

 duced 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 innovations 

 afterwards become separated by the 

 slow decay of the plant advancing 

 from below, and constitute indepen- 

 dent 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 



Fig. -ifxi.— sphagnum acutifolium ; part of the stem below the 

 apex ; a a the* male branches, b leaves of the primary stem ; ch peri- 

 chsetial branch with old still closed sporogonia (after Schimper, 

 XS-6). 



* Klinggraff, Bot. Zeitg. i860, p. 344. 



^ W. P. Schimper, Versuch einer Entwickelungsgeschichte der Torfmoose, Stuttgart 1858 (with 

 lany beautiful plates). [Russow, Beitr. z. Kenntn. d. Torfmoose, 1865. — Leitgeb, Wachsthum des 

 Jtammes und Entwickelung der Antheridien bei Sphagnum, Sitzber. d. Wien. Akad. 1869.] 



