400 S.A. r.R^'OPTIYTA. 



unable to endure extreme drought, and still seldom connected 

 with quite wet conditions. The ]>lanis composing this type live 

 on the soil, or on humus, rmd ])refer it to be usually moist, but 

 never continuously wet. Through the seasonal extremes to 

 which South Africa is subject the ]>roper conditions for this type 

 usually exist as forest carpet rather than under full ex|>osure 

 to sunshine, although there are s])ecies of Polytrichum, Pogona- 

 tum, DitrichuMi, Fissidens, Bryiiiii, Anomohryum, Brachythe- 

 cium, Trematodoii, etc-, which ])refer sunshine. 



Among the 'forest genera n\ this type may be mentioned: 



Atrichwn. Bryuin. Sterodoii, 



Rhodobrymii. Mtiiitm. Thuidinui. 



Fusi'dens. Campylopiis. Eiitodoii. 



Dicranella. Rhaphidosteqium. Redivigia. 



Funaria. Pseiidolcskea. Kaiitia. 



Lcucoloma. Microthaninium. Plagiochila. 



It is frequently the case that species of these genera occur 

 separately, forming monotypic associations, but it is also the 

 case that miscellaneous mixtures occur, containing many species. 

 In this association the permanency of the grouping depends 

 mostly upon continuous regularity of the forest cover; if it be- 

 come either more dense or more o])en the balance is tipset, and 

 some species gradually give place to others. 



Hygrophilous Associations. — The most marked but the 

 least common hygrophilous association in South .\frica is that 

 composed of Sphagnum, which usually occupies a saturated posi- 

 tion on rock, or on mud overlying rock, where the rock itself 

 prevents the escape, except b}' oxcrtiow, of a slowly meanderinjL'' 

 stream fully exposed to sunshine. This is often a m(;vnoty])ic 

 association, though Bartramiditla. Philonotis, Bryuni, Campy- 

 lopus, Blyttia, Symphogyua, Notoscyphus, and various grasses 

 or similar plants, occasionally become part of it, and as it raises 

 itself into drier conditions Antlweeros, Leucobryum, Mniuin, 

 etc., come in. followed later by certain phanerogams. 



Climatic and physical conditions seldom favour in South 

 Africa the formation of extensive Sphagnum moors or bogs 

 like those of Europe, consequently Sphagnum is rare, and 

 Meesiacese and Aulacomniacea^ probably absent. 



Ricch fhiitans and R. natans are both amphibious, and 

 have forms which float in slow i)ools. unattached to the soil, as 

 well as different land forms. 



But hvgrophilous associations are connected with every 

 stream, and some of the species alreadv mentioned as pioneers 

 under varying conditions become the climax type in a stream as 

 long as the conditions remain unaltered. 



.\ submerged bed of Aiieura. Duniortiera, IVardia, Cotio- 

 miirium or Hyophila mav last for a very long period without 

 effecting anv further colonization, and saturated cushions of 

 Philonotis. Fissidens. H\aroamhl\steginm, Campxlopus. Bryum, 

 Marchantia. etc.. frequently remain almost submerged for many 

 years, their only apparent object beino- to expose a saturated 



