SHORT NOTES 95 



occurs also in South-western France, near Archachon (!) ; in South 

 France, near Marseilles (sp.) ; and in Moravia (sp.). S. imsilla 

 Woods, S. gracillima Moss, and S. clisarticulata Moss, do not 

 appear in the Danish collection. The prostrate forms are also 

 poorly represented, but S. prostrata Pall, occurs. 



Generally, one's beliefs are confirmed that the perennial forms 

 of the genus are the most southern ; that the prostrate herba- 

 ceous forms are more southern than the erect ones ; and the erect 

 herbaceous forms are more abundantly represented in Southern 

 England than elsewhere. 



SHORT NOTES. 



Dissected Leaf of Horse-radish (Armoracia rusticana 

 Gaertn.). — The remarkable frequency of this form in a dry field 

 near Bognor in August last suggested that it might be correlated 

 with the long spell of dry, hot, sunny weather for which the 

 summer was remarkable. The phenomenon, which is well known 

 in this plant, consists in a reduction of the large surface by the 

 disappearance more or less of the mesophyll between the lateral 

 veins, and suggests an obvious adaptation to a diminished water 

 supply or to atmospheric conditions increasingly favourable to 

 transpiration. Generally several leaves of a plant were affected, 

 diminution of surface increasing in successively younger leaves. 

 I noticed a similar prevalency of the leaf-cutting in plants 

 growing in a small enclosure near home — just off West Hill, 

 Wandsworth. Thinking it might be worth while calling atten- 

 tion to the matter, I showed a specimen at a meeting of the 

 Linnean Society, and as several Fellows have written to me on 

 the subject since, I am writing this note for the Journal. Miss 

 I. M. Boper sent some striking specimens from Bristol, w^hich she 

 says " grew freely on a bank that had been raised at the edge of a 

 damp orchard on cold alluvial soil. Although the drainage would 

 be good on the slope, the situation w^ould never be dry. Observa- 

 tions in another district near Bristol show that the plants on a 

 rubbish-heap are each year much dissected, whilst those close by 

 at the edge of allotment grounds are normal, and on this account 

 I had associated the peculiarity with poverty of soil." Mr. H. S. 

 Thompson also writes that during the last twenty-five years he has 

 occasionally seen such forms in Somerset and elsewhere, particularly 

 on or near the sandhills about Berrow in Somerset ; he adds : " I 

 do not happen to have noticed if this form is especially frequent 

 in hot summers." Mr. J. E. Jackson, writing from Lympstone, 

 Devon, says: " I have read with some interest your note to the 

 Linnean on the dissected form of Horse-radish leaf, having had a 

 somewhat similar form in my own garden in the past summer. It 

 occurred on a young plant, probably two years old, the offshoot of 

 an older group which is in a damper and more shady position than 

 the plant bearing the dissected leaves, which, indeed, was close 



