Nr. 11 SUBAÉRIEL ALGAE FROM SOUTH AFRICA 



found both at Durban, which is a damp place, and at Saldanha Bay. 

 Nvith a very dry climate — two piaces being also veiy far apart 

 — allows the conclusion that the coniposition of the subaérial al gal 

 vegetation is rather homogeneous over large parts of the South 

 African continent, and mainly conformable to the foUowing 

 treatment. 



As compared with the frcshwater algae, it is only a very inconsi- 

 derable numljer of species and genera that occur as tnie aérophilous 

 algae, — that is, algae which are reduced to cover their consumption 

 of water by aljsorbtion of atniospheric moisture, and which survive 

 the usually frequent dry periods, on which they are condilional by 

 Iheir mode of living, without undergoing any particular resting 

 stages. 



In my material from South Africa I have been able to dis- 

 criminate 22 different species, 11 of which, or precisely one half, are 

 new ones. 5 of them even belong to genera, hitheiio unknown. 

 1 nis result is not surprisiiig, considering our extremely slight 

 knowledge of the subaérial algae of the southern hemisphere. In 

 addition to these were f urther encountered three species which 

 were not present in sufficient material for adequate determination. 



If compared on the basis of the present material, the flora of 

 subaérial algae in South Africa will be seen to have a comparatively 

 small nimiber of species in common with the one occurring in 

 northern Europe, viz. ChloreUa viilgaris, Pleurastnim lohatum. 

 Stichococcus variabilis, Hormidium flaccichini, Trentepohlia 

 aurea, Tr. umbrina, and Dactylococcopsis rhaphidioides. In the 

 main features, however, the gro w t h-f orms are identical 

 in type, but the bulk of the constituents belongs to other genera 

 and species — the floristic composition being rather 

 d i f f e r e n t. A comparison of the freshwater algae from the said 

 piaces, on the other band — if. e. g. Uie species from South Africa. 

 given by Fritsch, 1. c, are compared with the species occurrmg in 

 nortliern Europe — will evince a much closer conformity. 



Among phycologists the apprehension is generally reigning, thai 

 the tropics are more deficient in freshwater algae tJian e. g. the 

 temperate zones. Whether they are absolutely right, I somewhal 

 doubt, however. It must be kept in mind that by far most of the 

 coUections of algae brought home from the tropics, have been col- 

 lected by travellers, who have been mainly interested in other bran- 

 ches of science, and that the coUections thus ought to be considered 

 as rather accidentally brought together, and not giving any exhau- 

 stive idea of what is reall}^ to be found in the piaces. Further, for 

 a successful collection of freshwater algae is needed not a small 

 amount of experience. I therefore at present consider the accountii 

 of the supposed sparsity of freshwater algae in the tropics as not 

 yet quite established. 



