3 



so that the trunk is invested in an armour of leaf bases 

 each bearing its downwardly-directed leaf blade, more or 

 less of which is ultimately broken off by accident or burnt 

 away by fire. The downwardly-directed leaf bases are well 

 shown in pi. ii., fig- 2, where they are viewed from above, 

 cut obliquely in the transverse section of the stem. The 

 course of the leaf bundles within the stem offers points of 

 morphological interest, but they are not germane to the 

 questions at issue. 



The individual leaf is seen to have a long terete 

 blade some 75 cm. in length and only 1"25 mm. in cross 

 section, which is almost square. At the proximal end it 



passes into an enlarged leaf base, 

 expanded laterally into wings. 

 The base is some 5 cm. lonsr and 



O 



about 1'4 cm. in its greatest width, 

 while the thickness is at most 

 about 4 mm. (text fig. 1). In sec- 

 tion it has a horizontally elongated 

 diamond shape, but at the proxi- 

 mal end the winsrs become much 

 thinner, almost membranous. The 

 leaf is at first attached by the 

 whole base, but as it gets older the 

 wings become free from the stem 

 cortex, as will be seen below. 

 When young the leaf base is 

 whitish-yellow and has a highly- 

 polished appearance, being slightly 

 viscid to the touch. As it becomes 

 older the colour is more yellowish 

 and small flakes of resin appear 

 upon it. When old the leaf base 

 becomes very hard and tough, loses 

 its sheen, and takes on a brown 

 colour, often being coated with resin. The leaf bases remain 

 living for a much longer period than the laminas, probably for 

 several years, but by the time they have attained a horizontal 

 position with regard to the trunk they are dry and dead. 



The longitudinal section of the stem (pi. i., fig. 2) is 

 instructive, for it shows that the quantity of resin accompany- 

 ing the leaf bases increases as one passes basipetally down the 

 stem. This appearance, coupled with certain other observa- 

 tions, leads at first to the conclusion that the resin was secreted 

 by the leaf bases themselves. If the figure be carefully 

 examined there is seen to be a denser layer of tissue 

 immediatelv below the periphery of the stem. This is shown 

 b2 



Front and side view of 

 leaf base of Xanthorrhoea 

 quadrangulata showing 

 wings and marked hypo- 

 nastic curvature of the 

 old leaf base. x£. 



