SOME INTRODUCTIONS 249 



is completely established, but I have no doubt in my own mind that 

 to some wreckage containing Californian produce we must attribute 

 the occurrence of this Western American species in Ireland." The 

 note on Polygonum sagittaturn, which Mr. Druce found abundantly 

 in the Kerry locality recorded in Cybele Hibemica, shows how local 

 names may originate : " By a piece of good luck I am able to throw 

 some light on its method of introduction to the Irish flora. On my 

 return from Derrynane, I gave a lift on my car to a man who, see- 

 ing my vasculum full of this plant, said, ■ You have Dada's Weed.' 

 I asked him what he meant by using that name. He replied by 

 telling me that about fifty years ago a boat with a load of Indian 

 corn was wrecked on the coast near Castle Cove. The corn was 

 obtained by the man's father-in-law, who had a mill about a mile 

 or so up the small stream. The corn was duly ground into meal, 

 but the next year the Polygonum began to appear, and spread 

 rapidly, so that in time it was called by the children 'Dada's 

 Weed.' I may say it is not easy to see any trace of the mill, which 

 has been long ago demolished. Doubtless the prickly stems led to 

 its being conveyed by animals into the neighbouring bog, while the 

 stream itself carried the plant, or the seed of it, downwards to its 

 outfall into the sea. Had the course been longer, a greater extent 

 of the country would have been occupied by this invader." Mr. 

 Druce's paper also includes the description of a new variety of 

 Agrostis canina var. I avis Hackel in litt. — " 'Differt a typo foliis 

 omnibus planis latiusculis (circ. 2mm. latis) prorsus laevibus, 

 paniculae ramis spicularumque pedicellis laevibus, spiculis majus- 

 culis.' This grew near the summit of Brandon, and at once 

 attracted my attention, reminding me somewhat of the variety 

 scutica, which I gathered on Ben Eay, in Scotland, but I found 

 differed from it in several particulars. Professor Hackel therefore 

 names it as a new variety/ 1 



NOTICES OF BOOKS. 



Some Introductions. 

 Introduction to Plant Ecology. By the Rev. G. Henslow, M.A., 



F.L.S. Small 8vo, cloth, pp. x, 130. Price 2s. Stanford. 

 Wild 



DWARD 



Ho 



F.S.A. With 80 coloured plates. Pott 8vo, leather, pp. x, 

 263. Price 5s. net. Cassell & Co. 



\o Study Wild Flowers. By George Henslow, M.A., F.L.S. , 

 F.G.S. With coloured plates and other illustrations. Third 

 impression. 8vo, cloth, pp. 225. Price 2s. 6d. Keligious 

 Tract Society. 

 Mr. Henslow's object in writing his Introduction to Plant 



Ecology is to introduce the subject to teachers of botany in schools. 



In the earlier chapters, which are addressed more especially to 



Journal of Botany.— Vol. 45. [June, 1907.] t 



