358 



BOTANY. 



The genus Sphagnum was represented in the Tertiary (Miocene) of 

 Europe. 



Order Andrseacese. — In this small order ihe little plants of which 

 it is composed have a short-stalked sporogonium, raised upon a pseudo- 

 podium, as in the Bphagnaeem ; the sporogonium contains » layer of 

 spore-forming tissue, disposed as in the preceding order ; but the ripe 

 capsule opens by splitting into four longitudinal valves, in this remind- 

 iuit one of the Jungermanniaeem. In the growth of the sporogonium 

 the old archegonium is torn away at its base, and carried up as a cap 



(calyptra), which covers the apex of 

 the capsule. 



The principal genus is Andrcea, 

 represented in the United States by 

 a few alpine or sub-alpine species of 

 brownish or blackish rock -loving 

 Mosses. 



Order Phascacese.— These small 

 Mosses are peculiar in having but 

 a little development of leafy axis, and 

 in their persistent protonema. The 

 sporogonium is short-stalked, or ses- 

 sile, and the pseudopodium is very 

 short, or entirely wanting. The 

 spores are, in the simplest genus (Ar- 

 chidium), developed from a single 

 mother-cell, while in the higher ones 

 they develop from a layer of mother- 

 Fig. 846.-ir„;«,ria Awom^inca. A, «';''«• "1'^°^ ^« ill *l^e next order, 

 a young leafy plant, g, with sporogo- The capsule is iudehiscent, and the 



niiim gt 11 covered with the calyptra, c. -.,„-,,„ „_„ „„+ f„ i„ i •* j 



-B, le,ify plant, g, with nearly ripe sfio- S|'<"^<^« ^^^ ^et free only by its decay, 

 roxoiiium, /; c, thecalypira; a. seta. Tlie old archegonium persists as a 



C, longitudinal section of a capsule ; ^ „+ „ . ,, , 



e, e, columella ; a, operculum or lid, calyptra covering tUe capsule, 

 which will separate from the remainder The principal genera are Archidi- 

 of the capsule at a: p, peristome : s, „, , t% t . r«, 



spore-bearing layer ; A, air cavity Bur- **"». -f/ioscuw, and Briic/lia. The 

 rounding the columella, and crossed by species are terrestrial, and manv are 

 confervoid filaments; i. inferior con- * . ' •' 



n ction of the columella with the tissues annuals. 



Syed^™^C?about^40tiamlllrs!!^A";f; I- ^'f '^-t-'-y i^^'ooene) of Ea- 

 Sachs. rope a fossil spctiis of P/iascum has 



been found. 



Order Eryacese. — The plants of this order constitute the true 

 Mosses. They are usually bright green (in a few fjeiiera brownish), 

 and in the great majority of instances live upon moist ground and 

 rooks, or upon the bark of trees ; in a comparatively small number ' 

 of cases the species live in the water. 



In the development of their tissues and the complex structure of 

 Iheir sporogonia the Bryaceae clearly stand at the head of the Bryo- 

 phyte Division. The tissues, as indicated above (paragraph 458), attain 



