Marine Algae of the Cape Peninsula 53 



MARINE ALGAE OF THE CAPE PENINSULA; 



By Ellen Marion Delf, D.Sc. (Lond.), F.L.S., 



Temporary Lecturer in Botany at Cape Town University. 



Marine Algae are only revealed to the curious for part of each 

 day. This may perhaps account for the relatively slight know- 

 ledge which has been gained in the past with regard to the habits 

 and life histories of these plants. Until perhaps the last ten or 

 twenty years, the work of algologists was principally confined to 

 describing the appearance and occurrence of those seaweeds which 

 could be collected by dredging or by exploring the seashore at 

 low tides. Of late years, however, efforts have been made to 

 trace something more of the life histories of seaweeds, and to 

 understand their mode of life. These efforts have mostly been 

 made in the northern hemisphere, in England, America, and 

 Japan. Very little work of this kind has been done on South 

 African seaweeds; collectors have been numerous, and the work 

 of the late Mr. Tyson has greatly aided in drawing attention to 

 the large numbers of seaweeds found on these coasts. 



When the tide recedes we may find seaweeds on the short belt 

 in three characteristic habitats, in rock pools, exposed on rock faces 

 or ledges, or submerged in the deep water, only partly visible and 

 often wholly inaccessible to the collector. For the most part 

 these plants are attached at their base to the solid rock, or to some 

 sandy surface, by holdfasts or hapterons which reach out finger- 

 like processes in the case of the larger algae or minute threads in 

 the smaller forms, and firmly clasp the substratum. Since marine 

 algae live in water which is constantly subject to agitation, success 

 in attaching themselves is an important factor in the struggle for 

 existence. Other Algae, however, fasten themselves to their neigh- 

 bours. Plants of the green Alga, Ulva lactuca (the socalled sea 



