FORM AND POSITION OF THE TRANSPIRING LEAVES AND BRANCHES. 335 



requires no assistance, but where, on the contrary, the danger is often imminent that 

 water cannot be drawn from the soil in sufficient quantity to replace that lost by 

 exhalation. 



The phylloclades, moreover, are only a type of a large number of organs which, 

 in a word, all agree in this ; the edge or narrow side of the flattened exhaling 

 structure, not the broad surface, is turned towards the zenith. In many of the 



Fig. 83.— Plants with Leaf-lilie Branches (Cladodos). 

 1 Colletia cnruciata. 2 Carjnichelia australis. s Phyllanthics speciosus. 



vetches of the Southern European flora (Lathyrus Nissolia, Ochrus), but especially 

 in a large number of Australian shrubs and trees, principally acacias (Acacia longi- 

 folia, faleata, myrtifolia, armata, cultrata, Melanoxylon, decipiens, &c.), it is the 

 leaf-stalks which are extended like leaves placed vertically, and then the develop- 

 ment of the leaf -lamina is either entirely arrested, or has the appearance of an appen- 

 dage at the apex of the flat green leaf-stalk, or " phyllode ", as it is called. In many 

 Myrtaceae and Proteace<s, especially in species of the genera Eucalyptus, Leucaden- 



