Flora of Australia. o77 



WiTHANiA soMNiFKRA, Duu. (Solaiiaceae). "Narcotic Winter 



Clierry." 



Black Kock, Burnley, ElsteiiiAvick, and Domain (South Yarra). 

 J. W. Audas, 15/5/1918. 



This introduced plant is already widely spread and has now 

 .sufficiently established itself to be considered a naturalized alien. 

 Its creeping roots are difficult to eradicate, and it has slight 

 poisonous properties, which would tend to cause abortion. It is 

 native to the Mediterranean Regions and Africa. 



ULMUS CAMPESTRIS, L. "Common Elm." 

 {Rate of Growth). 



The growth in circumference of a fine tree standing in the 

 Herbarium grounds was followed over a year. A smooth surface 

 was prepared on a horizonal line, 5 ft. 6 in. from the ground, 

 .and the measurement taken with a tape. The circumference was 

 6 ft. 10 in., and no growth was shown from July until the end 

 of October. Growth began in November, but even at the middle 

 of December the increase barely exceeded a quarter of an inch. 

 The main growth took place from the middle of December to the 

 <ind of February, and amounted to \\ inches. The circumference 

 Avas then 6 ft. 11.5 in. It remained stationary until March, but 

 at the beginning of April had decreased by 0.2 of an inch, and 

 at the end of April by 0.3 inch. Probably this contraction is due 

 to the cambium layers being no longer so highly distended as when 

 actually growing. From April to June the circumference remained 

 ■constant at 6 ft. 11.2 in."^ 



A boring taken of the tree from which sections were made 

 showed that the canibial growth began nearly a month before any 

 apparent increase in external girth was shown. Evidently the 

 bark only begins to expand externally when the internal growing 

 tissues have produced a sufficient internal pressure upon it, and 

 the increasing pressure at first pushes the bark obliquely into 

 cracks or spaces previously developed. It is only when a certain 

 amount of cambial growth has taken place that the outermost 

 portions of an irregular scaly layer of bark move outward as a 

 whole, increasing the external diameter of the tree. 



1 The nieasureiuents were made hy a tape under constant tension checked against a wooden 

 «cale. 



