CRYPTOGAMS 



433 



a receptacle. The antheridial and archegonial receptacles are some- 

 times inappropriately referred to as moss flowers, but they have 

 nothing in common with the true flowers of vascular plants ; the 

 involucral leaves, which frequently have a distinctive structure, are 

 also known as the PERICH^ETIUM (Fig. 395). Between the sexual 

 organs there are usually present a number of multicellular hairs or 

 paraphyses. The moss plants may be monoecious, in which case 



em 



FKI. 389. Sphagnum fimbriatuni: A, A shoot with four ripe sporogonia. Sphagnum antti/olium 

 B, Archegonium with the multicellnlar embryo of the sporogonium em; C, a young sporo- 

 gonium in longitudinal section ; ps, pseuuopodium ; ca, archegonial wall or calyptra ; ah, neck of 

 archegonium ; spf, foot of sporogonium ; k, capsule ; co, columella ; spo, spore-sac with spores ; 

 K, ruptured antheridium with escaping spermatozoids ; F, single spermatozoid, highly 

 magnified. Sphagnum squarrosum : D, A lateral shoot with a terminal sporogonium ; ca, 

 ruptured calyptra ; d, operculum. (After W. P. SCHIMPER ; A, nat. size ; the other figures 

 magnified.) 



both kinds of sexual organs are borne on the same plant either in 

 the same or different receptacles ; or dioecious, and then the antheridia 

 and archegonia arise on different plants. 



The SPOROGONIUM of the Mosses ( 103 ) develops a capsule with 

 an axial COLUMELLA consisting of sterile tissue. The spore-sac 

 surrounds the columella, which accumulates food material and water 

 for the developing spores. Elaters are never formed. In the young 

 sporogonium outside the spore-sac, a well-developed assimilating 

 tissue is present; this is bounded by water-storage tissue and an 

 epidermis. In most Mosses stomata are found on the lower part of 



2 F 



