120 HORN EXPEDITION — BOTANY. 



Mueller (Pari. Report, Perth, 1883) ; thus, of a total of 332 species, deducting 

 therefrom ten which are maritime, 187, or GO per centum, are constituents of the 

 flora of the Finke Basin ; and V)y very slight extension of that area the actual 

 numl)er in common is 198. The Orders Zygophyllea?, Malvacea", Salsolaceje, 

 Leguminosa?, Myoporine*, and Gramineie, which are most largely represented, 

 have few species which are not common to the two areas. Tiie Myrtaceie of all 

 others show the greatest specific distinctness ; thus, of seventeen inhabiting Shark's 

 Bay, only three are in common, viz.. Eucalyptus fcr/niiia/is, E. cudes/iioidcs, and the 

 ubiquitous E. rostra/a. So also the flora of Nickol Bay exhibits the same affinity, 

 as, of a total of 185 species listed by Baron F. von Mueller (Pari. Rep., Perth, 

 1881), 110, or 60 per centum, occur in the Larapintine region. 



This type of vegetation constitutes a very large proportion of the whole 

 Larapintine flora ; its species are either immigrants from tlie Oriental Botanical 

 Province or are endemic species of extra-Australasian genei'a. The truly Australian 

 forms, excepting perhaps among Acacia, Eucalyptus, and a few others, are most 

 frequently gregarious in isolated colonies, sometimes occupying a few square yards, 

 or even as much as several square miles. Of the former, Diplopeltis Stuartii, 

 Catflsperma Muelleri, and Ptychosema ttifoliolatum may l)c quoted as examples, and 

 Brachysevia Cha)nbersii and GrevilUa eriostacJiya of the latter. On several 

 occasions, in tlie earlier part of our travels, I had passed by an unfamiliar plant, 

 hoping it would extend as far as our halting-place, near approaching ; but in the 

 majority of instances the expectation was not realised. Profiting by this 

 experience, I afterwards let no plant unknown to me go ungathored. It is 

 because of the sporadic distribution of many of the Australian species that it is 

 probable that a not inconsiderable number remain to be discovered. 



The aggressive nature of the alien plants is exhibited not only by their 

 extensive distribution, but also by their ability to adapt themselves to extremes of 

 soil and climate. Such species, among others, as Tri/nilus terrestris, Cleome 

 viscosa, Malvastrum spicatunt, Boerhaavia diffusa, Sahola kali, Mollui^v hirta, and 

 Pflllic/iia Zeylauica range from the r'iver-banks and loamy plains to the sandiiills, 

 and surmount the highest elevations of the rocky country. No endemic species 

 .shows such ubiquity, not even Triodia pungens, which seems confined to absolutely 

 sterile tracts, no matter however great the elevation. Chenopodium rliadiiio- 

 stacliyum, though not a common plant, has however an equal altitudinal range. 



((/) The Saxatile Vei^^etation. — I cannot write of a mountain flora because tlie 

 number of actual species on the table-lands and other higli-level tracts is absolutely 

 few. The exploration of Station Range, of about 500 feet elevation above Tempe 



