BOTANY OF TERRA AUSTRALIS. 45 



CASUARINE/E. The o-emis Cnxuaruia is ccrtainlv not 

 referable to any natural order of plants at present estab- 

 lished ; and its structure being now tolerably understood, 

 it maybe considered a separate order, as Mirbcl has already 

 suf>-p;ested.^ 



The maximum of Casuarina ajipcars to exist in Terra 

 Australis, where it forms one of the characteristic features 

 of the vegetation. Thirteen Australian s[)ecies have already 

 been observed ; the greater number of these are found in 

 the principal parallel, in every part of which they are almost 

 equally abundant ; in Van Diemen's Island the genus is 

 less frequent, and within the tropic it is comparatively rare ; 

 no species except Casaarina eqiiisefifolia having been ob- 

 served on the north coast of New Holland. Beyond Terra 

 Australis only two species have been found, namely, C. 

 equisetifolia, which occurs on most of the intratropical 

 islands of the Southern Pacific, as well as in the iMoluccas, 

 and exists also on the continent of India ; and C. 7iodiJlora, 

 which is a native of New Caledonia. 



In the male flowers of all the species of Casuarina, I 

 find an envelope of four valves, as Labillardiere has already 

 observed in one species, which he has therefore named C. 

 quadrivalvis.^ But as the two lateral valves of this en- 

 velope cover the others in the nnexpanded state, and appear 

 to belong to a distinct series, I am inclined to consider 

 them as bractese. On this supposition, which, however, I 

 do not advance with much confidence, the perianthium 

 would consist merely i)( the anterior and posterior valves, 

 and these, firmly cohering at their apices, are carried up by 

 the anthera, as soon as the filameni begins to be produced, 

 while the lateral valves or bracteoe are persistent ; it follows 

 from it also that there is no visible perianthium in the 

 female flower, and the remarkable economy of its lateral 

 bracteae may, perhaps, be considered as not only affording 

 an additional argument in support of the view now taken i^n 

 of the nature of the parts, but also as in some degree again 

 approximating Casuarina to Conifer ce, with which it was 

 formerly associated. 



' Annales da mus. l{],p. 151. - PlanL Xov. IIoll 2, />. 07, I. 21 S. 



