Chapter V. 



THE MIMOSA FAMILY. 



This family is closely related to the Peaflowers, so much 

 so that the two are commonly linked together. The fruit 

 and seed are alike, but the flowers differ. In Tasmania 

 we have many species, but they all belong to one genus, 

 Acacia, locally called Wattle, or, in some instances, 

 Mimosa. This latter name should not be used, as we have 

 no true Mimosas. 



Acacia is the largest genus of Australian plants. They 

 are all shrubs or trees; something like three hundred and 

 fifty species are described. Out of all these only one 

 species extends beyond the Commonwealth. Other forms 

 occur in Asia and Africa, but are nowhere as abundant 

 as they are with us 



In Tasmania we have seventeen species, and for the sake 

 of convenience we can divide them into three groups accord- 

 to the shape of their leaves. One group has divided 

 leaves, a second has flat, blunt leaves, while in the third they 

 are simple and prickly. Of the first we have three forms: 

 Silver Wattle, whose ultimate leaflets are very narrow and 

 clothed with delicate hairs, giving a bluish tinge to the 

 foliage it flowers in the spring; Black Wattle, in which 

 the leaflets are the same shape, but nearly hairless and 

 dark-green it flowers at midsummer; and River or Green 

 Wattle, whose leaflets are broad, and whose flowers 

 mature in the autumn. Of the broad, flat-leaved forms, 

 Blackwood, Native Willow, and False Booby alia are the 

 commonest- There are several prickly-leaved forms, and 

 they are mostly known by the one name, Prickly Mimosa. 

 All these forms, when young, have divided leaves, and in 

 response to injury at least Blackwood may throw out such 

 at any period of its life. The simple forms are produced 

 by broadening of the leaf -stalk and suppression of the leaf- 

 lets. This is an adaptation to make them better suited 

 for our very sunny climate. This reduction of leaf surface 

 and thickening of substance, which may, however, be 

 brought about in a variety of ways, is very common in 

 sunny countries, especially where rainfall is not corre- 

 spondingly heavy. It is very noticeable in Australia in 

 all sorts of families. 



