THE FERNS OF SOUTH AFRICA 
margin. But quite a large number of our ferns are not 
damaged by drought, and are regularly subject to it, growing 
not only in the outskirts of the forests but also along rocky 
banks, or in ditches, and others even in swamps. A few species 
occur only in swamps ; many prefer to be close to waterfalls 
or running streams, and one species ( Acrostichum aureum) 
has a partiality for being just above floodmark in tidal 
lagoons. 
The flat sandy country between the mountain range and 
the sea in Northern Zululand and throughout much of Por- 
tuguese East Africa has very few ferns, those present being 
either of the hardiest nature and common kinds, or else of 
peculiar requirement such as Acrostichum aureum on the 
lagoon mud, Dryopteris thelypteris and D. gongylodes in 
swamps, Ophioglossum in sandy grass-land, Stenochlaena as 
a climbing epiphyte, or Platycerium as an epiphyte high 
up on the trees, or Ceratopteris floating on pond water. 
Equally peculiar are those xerophytic species which belong 
to or extend into the dry regions, including Cheilanthes hirta , 
Pellaea hastata , P. viridis and the various western species, 
some of which are little known and seldom seen in perfect 
condition through being brittle and easily damaged, and also 
through growing where collectors seldom visit and where 
those who do so do not have the best conveniences for drying 
good specimens. Notable among collections from this dry 
class of country is the collection made by the Percy Sladen 
Memorial Expedition under Dr H. H. W. Pearson in the 
dry regions of Namaqualand and beyond, the ferns then 
collected including Mohria caffrorum , Cheilanthes multifida , 
C. hirta , C. induta , Adiantopsis capensis , Asplenium adiantum- 
nigrum , Ophioglossum capense , Pellaea auriculata , Pteridium 
aquilinum , Blechnum australe , Adiantum capillus-veneris , Os- 
munda regalis , and Todea barbara. This group is repre- 
sentative of the ferns of carroid districts, the last three being 
present only where there is regular soil-moisture but with- 
standing the other conditions. 
Some of these carroid ferns have amazing vitality ; one 
small plant of Pellaea auriculata collected by myself was left 
