SPHAGNACE^E. 



[ 708 ] 



SPHAGNACE^E. 



tides, more rarely in brackish ditches, or 

 upon decaying marine Algse. 



The best distinctive marks of this species 

 are, the subacute extremities, combined 

 with the short filament and littoral habit. 



S. Jacobi. Filaments elongated, their ends 

 usually attenuated ; ordinary cells subsphe- 

 rical; vesicular cells spherical; sporangial l 

 cells oblong or cylindrical. Ralfs, /. c. pi. 8. 

 fig. 8; Eng.Bot. 2826. fig. 2. Forming thick, 

 bluish-green, gelatinous masses, from which 

 the filaments issue in long rays. Fresh- 

 water. 



S. elastica (PI. 8. fig. 3). Dissepiments 

 conspicuous ; ordinary cells quadrate ; vesi- 

 cular cells elliptic; sporangial cells cylin- 

 drical, truncate. Ralfs, L c. pi. 8. fig. 9. 

 Cylindrospermum elongatum, Kiitz. Tab. 

 Phyc. i. pi. 99. fig. 3. Forming a tender 

 stratum, of a deep bluish colour, in bogs. 



** Filaments moniliform; sporangia turgid, 

 much broader than the ordinary cells. 



S. Broomei, Thwaites. Filaments elon- 

 gated ; ordinary cells suborbicular ; vesicu- 

 lar cells barrel-shaped or elliptic ; sporangial 

 cells elliptic, catenate. Ralfs, I. c. pi. 7. 

 fig. 10. Forming a firmish bluish- or yel- 

 lowish-green stratum in brackish ditches. 



S. Berkeleyana, Thwaites. Ordinary i 

 cells spherical or slightly compressed ; vesi- ' 

 cular cells spheroidal, compressed, as broad 

 as the large, turgid-elliptic, sporangial cells. 

 Ralfs, L c. pi. 8. fig. 11. In brackish 

 ditches. 



S. Mooreana, Ralfs. Ordinary cells sub- 

 spherical; vesicular cells barrel-shaped, 

 much narrower than the large, broadly 

 elliptical sporangial cells. Ralfs, /. c. pi. 8. 

 fig. 12. An Irish species. 



*** Dissepiments obscure ; cells longer than 

 broad. 



S. leptosperma (Kiitzing). Filaments 

 elongated, not constricted at the dissepi- 

 ments ; ordinary cells longer than broad, 

 confluent ; vesicular cells elliptic ; sporan- 

 gial cells linear. Ralfs, 1. c. pi. 8. fig. 13. 

 Cylindrospermum leptospermum, Kiitzing, 

 Tab. Phyc. i. pi. 99. fig. 2. Forming large 

 shapeless gelatinous masses in still waters, 

 varying from deep green to yellowish green, 

 or, when the filaments are comparatively 

 few, nearly colourless. Distinguished espe- 

 cially by the "confluent ordinary cells with 

 obscure dissepiments." 



SPHAGNA'CE^E. A family of Clado- 

 carpous Mosses, of peculiar habit, growing 



in bogs &c., distinguished especially by the 

 mode of branching, the structure of the 

 leaves, sporanges, and antheridia, and by 

 the absence of roots, except in the early 

 stages of growth. 



The stem of the Sphagna is composed of 

 three layers of cells, a cortical, a medullary, 

 and an intermediate prosenchymatous layer, 

 which finally becomes somewhat woody. 

 The primary axis is indefinite in its growth ; 

 the lateral axes, sterile or fertile, are an- 

 nual. The secondary axes are fasciculate ; 

 and being pendent or recurved upon the 

 stem, they fulfil in some measure the func- 

 tion of roots. The leaves are remarkable for 

 their cellular structure, being composed of 

 two kinds of cells namely, narrow and 

 elongated cells filled with chlorophyll, con- 

 joined into a kind of network, the meshes 

 of which are occupied by large hyaline cells. 

 The hyaline cells contain, in all but one 

 exotic species, a spiral or annular secondary 

 deposit (PI. 48. fig. 25) characteristic of 

 this family. These large cells also become 

 opened by regular circular pores at a certain 

 stage of growth. 



The inflorescence is monoecious or di- 

 oscious. The antheridia are produced singly 

 in the axils of perigonial leaves at the club- 

 shaped tips of short branches. They are 

 pedicellate and roundish, like those of the 

 Liverworts ; they produce biciliated sper- 

 matozoids. The archegonia are found about 

 four together, sessile, in a tuft of perichae- 

 tial leaves occupying the axis of a fascicle 

 of branches, the receptacle subsequently 

 elongating into a peduncle, bearing a glo- 

 bular capsule, entirely surrounded by the 

 calyptra. The calyptra is ruptured near the 

 middle, the lower part persistent and con- 

 tinuous with the fleshy vaginule, within 

 which the capsule is seated on a bulb-like 

 pedicel ; peristome none ; operculum flattish, 

 thrown off with elasticity. Spore-sac 

 wanting ; columella short, not reaching the 

 mouth of the capsule. Spores apparently of 

 two kinds, some enclosed four together in 

 parent cells, others smaller, sixteen in one 

 parent cell; the former fertile, the latter 

 sterile, occuring either together or in di- 

 stinct capsules. The spores in germinating 

 produce a Marchantioid body, very different 

 from the confervoid mass of ordinary mosses. 



British Genus. 



Sphagnum, Dill. Character that of the 

 order. Nine species occur in Britain, some 

 common on every bog, distinguished by 



