of the Australian Flora.] INTRODUCTORY ESSAY. 



The rarity in both of Aroideee, Laurineee, and all Rubiaceai except the Anthosperrnece, is also worthy 

 of notice. With regard to the Natural Orders enumerated above, their genera are almost unexcep- 

 tionally different in the two countries. T find that of 1,000 South African genera of flowering plants, 

 only about 280 are Australian ; of these about 160 are also common to Europe, and 130 to India, 

 leaving Callitris, Encephalartos, Restio, Hypolozna, and Anyuilluria, confined to South Africa and Aus- 

 tralia, and 10 more common to these countries, together with New Zealand and extratropical America. 



On the other hand, South Africa contains upwards of 220 European genera, of which 80 are not 

 Australian, and of these upwards of 60 are north temperate forms. We have hence the very curious 

 fact that in point of numbers Australia represents generically the European Flora better than South 

 A.frica does ; but that the South African Flora contains a larger proportion of very northern European 

 genera (not species) than Australia does. This is no doubt because many of the so-called European 

 genera of Australia are more properly Asiatic, and spread thence in both directions, towards Europe 

 and towards Australia. 



Before dismissing this subject, it is as well to glance at the differences between these Floras, which 

 may shortly be summed up. South Africa abounds in Campanulacem, which are very rare in 

 Australia, where the very closely allied Orders Stylidiete and Goodeniaceee abound. The true Erictce, 

 which swarm in certain districts of South Africa, are all but wholly absent in Australia, being repre- 

 sented there by t.ieir suborder Epacridea. Succulents are, comparatively, extremely rare in Austra- 

 lia, which almost wholly wants those conspicuous features of South African vegetation the CrassulacetB, 

 Ficoidete, fleshy Aschpiadem, Liliaceee (Aloes), and Euphorbias. 



I have given (p. xxxiii.) a list of the five Orders which abound more in South Africa than in any 

 other country but Australia, and are therefore highly characteristic of both these. I shall now give 

 the contrasting ordinal dissimilarities of each. 



The following Orders are represented in the South African Flora, but are either comparatively 

 rare or absent in Australia : — 



Fumariaceas, absent in Australia. 



Dipsaceae, absent in Australia. 



Arctotidea? (tribe of Comp.). 



Ericeas. 



Campanulaceas. 



Stilbinese (Verben.), absent in Austral 



Selagineas (Verben.), ditto. 



Asclepiadeae. 



Podosteniaceae, ditto. 



Saurureas, ditto. 



Rafflesiacete, absent in Australia. 



Cytineae, ditto. 



Betulaeeae, ditto. 



Salicmeas, absent in Australia. 



Hypoxideae. 



Temperate Australia contains the following Orders that are rare or absent in South Africa 



Kesedace<£, 



ditto. 



Bixaceae. 





Tamariscineae, 



ditto. 



Geraniaceae. 





Oxalideae. 





Caryophylleffi. 





Ficoideae. 





Rosacese. 





Bruniaceas, 



ditto. 



Loaseae, . 



ditto. 



Penaeaceae, 



ditto. 



Begoniaceas, 



ditto. 



Crassulaceas. 





Yalerianeas, 



ditto. 



Dilleniaceas, absent in South Africa. 

 Magnoliaceae, ditto. 



Monimiaceas. ditto. 



Sapindaceas. 



Tremandrea?, absent in South Africa. 



Pittosporeae. 



Stackhousieas, ditto. 



Halorage*. 



