37G Transactions. — Botany. 



require to be doubled or trebled to represent adequately the number of non- 

 indigenous plants. I hope that this small contribution may be the means of 

 inciting other members of the Institute and Field Club to make known any 

 plants which they have discovered, and which are not mentioned by me. 



Art. LVII. — On Mottled Kauri. By James Stewart, C.E. 

 [Read before the Auckland Institute, 26th Aiigust, 1874.] 



Kegarding the origin of the rich mottled shading of some kauri trees, 

 considerable diversity of opinion exists, some ascribing it to a timber disease, 

 while others believe such trees to belong to a variety of the kauri. The 

 slightest examination, however, seems to show that this is no variety, but a 

 peculiarity due to an abnormal growth in the sap-wood and bark. The mottled 

 kauri is rather a rare tree, but a young mottled kauri is rarer still. 



If it were a variety we should expect to find the markings in the roots 

 and stumps; on the contrary, it is believed those parts are never affected, and 

 for some distance up the trunk the timber is often just like that of other kauri. 

 Allowing then, that it is to an abnormal state of the growth of the tree we 

 owe this rich and valuable furniture wood, an enquiry as to the operating 

 cause may not be uninteresting. 



On examining a portion of the outer timber and bark of a highly mottled 

 tree such as the specimens now exhibited were cut from, we see the bark 

 entangled in the sap-wood, being pitted and streaked in some places very 

 deepl}'-. The specimens are all sawn from a board showing bark and sap-wood, 

 and little or no heart timber. The bark has mostly fiillen away during the 

 seasoning, but the action and growth of the mottling are very clearly shown 

 by examining the sections across grain. The bark is shown to become 

 entangled in the ligneous growth, and has been surrounded and retained, 

 sometimes in cells, sometimes leaving only a trace of non-fibrous barky matter 

 in thin flakes, causing shaded parts, broad or narrow, according as the 

 timber is cut relative to their planes. Nearest the bark the mottlings are 

 nearly pure bark, and as they are found in the tree away from the surface, 

 they are observed to be more and more of a ligneous structure. A 

 close study of the specimens will convey an impression of the connection 

 between the bark and the markings, better than any written description can 

 do, but it is to be observed that all around this, in some degree foreign sub- 

 stance, the true wood is shaded and marked in itself, just as it is to be 

 observed in knotty timber, and as the timber is transformed to the state of 

 heartwood, a deposit of gummy and ligneous matter seems to transform even 

 the largest of the imprisoned flakes into veritable woody fibre. 



