Feb., 1909.] 
The Classification of Plants, IV. 45 1 
elastically elongating stalk; sporangium without columella, 
usually with elaters, indehiscent, irregularly dehiscent at the top, 
or splitting into four valves from the summit, rarely developing 
an operculum. 
27. Sphagneae. Bog-mosses. 250 species. 
Gametophyte a stem-like, erect, light, gra} r -green frond with¬ 
out a true central strand but with large cortical cells, bearing 
numerous scales without a costa but with two kinds of cells, 
narrow ones with chlorophyll and large ones without, but with 
holes in the walls; rhizoids septate; protonema finally thalloid and 
flat; fruiting plant developing one or more pseudopodia which 
support the sporophytes. Sporophyte without a stalk but 
with an expanded foot; sporangium with a shallow dome-shaped 
spore cavity in the upper part and with an operculum but with¬ 
out a peristome, elaters, or air cavities. Growing in bogs and 
wet places. 
28. Andreaeae. Granite-mosses. 105 species. 
Gametophyte a stem-like, erect frond without a central 
strand, bearing numerous scales without or with a costa; rhi¬ 
zoids consisting of cylindrical masses or plates of cells; protonema 
more or less thalloid. Sporophyte without a seta but with a foot 
and finally carried upon a pseudopodium; sporangium without 
air cavities, splitting into four or more valves which are at first 
united at the top, spore cavity cylindrical dome-shaped with an 
upward projecting central columella; elaters none; calyptra pre¬ 
sent on the sporophyte. Caespitose plants of a dark brown color 
growing on rocks. 
29. Musci. Mosses. 12,500 species. 
Gametophyte a stem-like, erector prostrate frond usuallvwith 
a well-developed central strand and with costate scales; rhizoids 
filamentous, septate; protonema usually well-developed and fila¬ 
mentous, sometimes persistent; pseudopodium none. Sporo¬ 
phyte well-developed with sporangium, foot, and usually with 
a well-developed hypophysis and a seta with a central strand; 
sporangium usually with an operculum and a central columella 
extending entirely through the spore cavity, usually with a well- 
developed peristome and air spaces often communicating on the 
outside with stomata; venter of the archegonium enlarging and 
usually ruptured at the base, the upper part being carried on top 
of the sporangium as the calyptra. 
30. Anthocerotes. Horned Liverworts. 103 species. 
Gametophyte a dorsiventral thalloid frond without scales or 
with imperfectly developed scales but with unicellular rhizoids; 
sexual organs imbedded in the tissue of the thallus; protonema 
small and transient. Sporophyte with a slender horn-like or 
