1907- 1 77 



NOTES. 



BOTANY. 



Leaf-pitting in Arum maculatum. 



Some four years ago attention was drawn in this Journal (Jr. Nat. xii., 

 p. 7S) to a curious form of leaf-pitting in the Common Arum observed at 

 two stations in Co. Dublin, Kilbogget, near Ballybrack, and Newcastle, 

 near Saggard. In the discussion which ensued no satisfactory h3'po- 

 thesis was suggested in explanation of this pitting or pseudo-blistering 

 cf the Arum leaf, but the negative result was arrived at that the pitting 

 was not morbid, that is to say, was not due to insect or fungus infection. 

 Dr. Pethj bridge, in a very interesting contribution (Ir. Nat. xii., p. 145), 

 pointed out that the spotting of the Arum leaf, observed with greater or 

 less frequency in many parts of the British Isles, had been shown by the 

 researches of Stahl in the Jena Botanical Garden to be permanent or 

 hereditary, at least in this sense, that it was repeated in the same plant 

 from year to year. Having grown in my garden for three years some 

 plants of the Newcastle Arum referred to above, I find that the pitting 

 no less than the spotting of the leaves is hereditary in the same sense # 

 The plants when gathered at Newcastle in 1904 had leaves plentifully 

 spotted and pitted, the pittings being on the upper surface of the leaves, 

 with answering prominences on the back or lower surface. Next year's 

 leaves of these plants were well above ground in the garden and partially 

 unrolled by the 4th February, 1905. They were spotted and pitted pre- 

 cisely as in the previous year, the pits being recognizable quite as early 

 as the spots. With the growth of the plants, both spots and pits became 

 more pronounced, until finally the leaves assumed an appearance indis- 

 tinguishable from that of the plants in their original hedgerow habitat. 

 A similar development took place in the garden plants in the spring of 

 1906, and again for a third time in the spring of the present year, the 

 pittings of 1907, like those of 1904, being accurately coincident with and 

 strictly confined to the parts of the leaves marked by brown spots and 

 blotches. So far none of the plants have flowered with me in cultiva- 

 tion, so that I have had no means of deciding whether the pitting is 

 transmissible by seed. 



N. Coi,GAN. 

 Sandycove. 



I may add that for three years I have grown in my garden a spotted 

 but unpitted plant, obtained by Dr. Pethybridge near Greenhills, Co. 

 Dublin. It also has retained its character constantly. 



R. IX Praeger. 

 Dublin. 



