662 



THE ADVENTITIOUS ROOTS OF MELALEUCA 

 LIN A RII FOLIA Sni. 



By C. T. MussoN and W. M. Caiine, Hawkesbury Agri- 

 cultural College. 



(Plates xviii.-xix.) 



It has long been noticed at Richmond, N. S. Wales, and near 

 Sydney, that the Swamp Teatree{J'/e^a/eitcn linariifoUa Sra.)has 

 its very papery bark more or less covered and interpenetrated 

 by fine, irregularly branching growths having all the appeai'ance, 

 at first sight, of some climbing plant making free use of the stem 

 as a support. In reality they are outgrowths from the stem, 

 which, growing through the l)ark now reach the air, travel over 

 the tree for varying distances, then re-enter the bark and end, 

 usually, low down therein close to the wood; probably only now 

 exposed through wearing away of the outer bark. Within the 

 bark they flatten out, and branch in such a way as to accommodate 

 themselves to a necessarily restricted location between the bark 

 sheets, which are sufficiently loose to allow of their penetration 

 in any direction. These adventitious roDts arise below the cam- 

 bium, and are covered with a protective bark very similar to that 

 of the twigs, their centres being occupied by a cylindrical fibro- 

 vascular strand. From one to three feet in total length, even 

 longer in some cases, they vary in diameter from less than 2 mm. 

 to as much as 1 cm.; in some cases they assume even stem-like 

 dimensions; for in a few old trees such growths, arising at some 

 point in the stem 10 or 12 feet above the ground, have eventually 

 reached it, struck root, and become Banyan-like secondary stems, 

 though remaining closely appressed to the parent-stem. A few 

 of the smaller growths arising near the ground have also entered 

 it and struck root. The distal ends of these bark-penetrating 

 root-growths show nothing resembling hairs or a root-cap; they 

 are paler in colour than the rest of the enclosed root, which is 



