MISCELLANEOUS PLANTS 



167 



plant is found in these archipelagos, whether in Hawaii, Tahiti, the 

 Marquesas, Rarotonga, Samoa, Tonga, Fiji, etc., the botanist refuses 

 it a place in the indigenous flora. Its absence from the native floras 

 of these islands would be readily understood, if it was not at home 

 on the western borders of the Pacific, that is to say, in the regions 

 comprising South-eastern Asia, Malaya, and North Australia, whence 

 the Polynesian plants have been in great part derived. Yet it would 

 be quite consistent if America was the home of the plant, since 

 except in the very distant past there have been very few connections 

 between the American and Polynesian floras. The indications 

 would seem to be, as inferred by Hillebrand in the case of Hawaii, 

 that the tree was introduced by the early Europeans into the Pacific 

 islands. 



With the issue thus a little narrowed we will now discuss its dis- 

 tribution more in detail; but numerous difficult questions at once 

 present themselves. Why should this particular species of Acacia, 

 we may ask, wander round the tropics of the globe, when hundreds 

 of others remain restricted to their homes, principally in Australia 

 and South America? Hemsley, writing about thirty years ago, 

 remarked that of the three hundred Australian Acacias, this is the 

 only non-endemic species (Chall. Bot., IV., 148). Found over most 

 of the warm regions of the globe, it so often impresses the botanist 

 with the appearance of being indigenous that, as we have seen, 

 various regions have been assigned as its home. Long ago Willde- 

 now placed its home in the West Indies and particularly in San 

 Domingo (quoted by Schmidt in his Cap Verdische Flora). How- 

 ever, it will be apparent from its behaviour in the Hawaiian Islands, 

 as described later on, that the plant soon adapts itself to a new 

 locality and spreads rapidly. The tendency on the part of many 

 introduced plants to become thoroughly naturalised in a short space 

 of time is well illustrated in this case, and the modern botanist 

 with a larger experience of such cases is better able to discriminate 

 in such matters. 



But a further difficulty would present itself in the variety of stations 

 selected by the plant. Though they would be all consistent with 

 the behaviour of a xerophilous plant, their variety would tend to 

 complicate the problem concerned with the home of the species. 

 It is equally at home in the arid plains of the elevated interior of 

 Mexico, at the margin of the sea beaches in the West Indian Islands, 

 and amongst the trees in the loamy soil bordering the mangrove belt 

 in Jamaica and elsewhere. It may cover the low-lying plains of 

 the sea border with an impenetrable bush as on the Gulf margins 

 of Texas, or it may with other trees fringe the dry beds of streams 

 in the prairies of the same region. Such is its behaviour in the 

 New World as indicated by Harshberger and others, but the variety 

 of its stations might be illustrated from other parts of the globe. 



Its littoral habit may be first dealt with. Though more typical 

 of the belt of trees that immediately border the sandy beach, it 

 accompanies certain of these trees when they grow at the edge of a 

 coastal or estuarine swamp. In Java, according to Schimper (Ind. 

 Mai. Strand Flora, pp. 67, 122), it is an essential constituent of the 



