4 AN ENUMERATION OF THE BRUNIACE^ 



formation in that region, for, as Eodgers " has stated, "The for- 

 mation traverses more or less interruptedly the whole Colony 

 from the Bokkeveld Mountains (Ceres division, where the Bruni- 

 aceae are represented by ten species) to the Cape Peninsula, and 

 thence to Port Elizabeth, where the formation enters the sea and 

 with a wide curve reappears at the mouth of the St. John's 

 Eiver, and thence extends eastwards through Pondoland towards 

 Natal." 



Analogous cases are evident on the Cape Peninsula, for with 

 the disappearance of the Table Mountain sandstone, as on Signal 

 Hill, all traces of the Bruniacese vanish, and similarly the wide 

 low-lying sandy expanses or flats which separate the Stellenbosch, 

 Caledon, and Table Mountain ranges are destitute of members 

 of this group, except for the ubiquitous Staavia radiata and an 

 occasional Berzelia. Altitudinal range does not suffice to explain 

 this distribution, as several species enjoy a fairly large range; 

 thus Berzelia lanuginosa occurs at elevations from 300-3500 ft. ; 

 B. ahrotanoides, 50-3500 ft. ; Staavia radiata, 50-3500 ft. ; S. 

 lateriflora, 50-1500 ft. ; Brunia nodiflora, 50-3000 ft. ; Pseiido- 

 bceckea cordata, 1-4000 ft., &c. 



The paucity of the species in the centre of the Colony is in my 

 opinion attributable to the absence of the geological formation 

 under consideration, and, moreover, to the exceedingly cold nights 

 and extremes of heat and cold which prevail, for, as Schimper 

 rightly argues, it is the absolute maximum and minimum, not the 

 mean annual temperature, which are of the greatest moment to the 

 life of plants. 



The absence of specialized structures for facilitating the dis- 

 persal of fruits or seeds has doubtless also contributed in pre- 

 venting a wider diffusion of the order. 



The extreme localization of certain species is worthy of note. 

 Staavia Dodii is confined to a rocky ridge on the southern 

 extremity of the Cape Peninsula, while Audouinia capitata, a 

 subsocial though more abundant plant than the preceding, is 

 restricted to the same area, and also on a similar geological forma- 

 tion on the other side of False Bay. Mniothamnea callunoides, a 

 monotype, has only been discovered by the indefatigable Burchell 

 on the Kampsche Berg, and on a mountain peak near Swellen- 

 dam, and similarly Berzelia Burchellii, another of his discoveries, 

 is only recorded from Garcias Pass, Caledon. Staavia Broionii 

 has been detected on the Hottentot's Holland Eange, while speci- 

 mens of Thamnea Massoniana, collected by Masson in the vicinity 

 of Stellenbosch, illustrate the circumscribed area of distribution of 

 this species. The adjoined table is suggestive of the diffusion of 

 the genera in general. 



The Order is destitute of any economic properties, save that it 

 yields occasional firewood, and affords material for the flower- 

 vendors at the Cape. Formerly several of the species w^ere culti- 

 vated in England and extensively on the Continent on account of 



* An Introduction to the Geology of Cape Colony, p. 106, 1904. 



