450 Scientific Proceedings^ Royal Dublin Society. 



region. All the weeds found in a sample are needed as determinants 

 for an East European sample. Such are : — Silene dichotoma, Ehrh. 

 Saponaria vaccaria, L. {Vaccaria segetalis, Q-arke.), Glaucium coniicii- 

 latum, Crtz., Berteroa incana, DC, Erysimum orientale, E.. Br., Hibiscus 

 Trionum, L., Anthemis austriaca, Jacq., Carduus ucanthoides, L. 

 7. South American. (Chili, Argentine Republic.) 



Ceratochloa austmlis, Sprge., is an endemic weed here. 3Iediccigo 



denticulata, Willd., M. '.naculafa, Sibth. (ilf. arabica, Huds.), Melilotus 



parviflora, Desf., Ammi visnaga, Lam., and Cuscuta racemosa. Mart., 



are also all guides. C. racemosa ("Chili dodder"), indigenous in 



S. America, now occurs as a weed in southern France, and is spreading 



in other countries. 



Dr. Stabler urges on each Station the duty of collecting information as 



to the seeds of the indigenous weeds found in the agricultural seeds 



produced in its district, and placed on the market for sale. Thus, for 



Ireland, information is needed on the indicator- weeds in Perennial Rye and 



crested dogstail. As these two grass-seeds command a good price, sure 



indicators of their genuineness would be of a distinct advantage to both 



producer and buyer. All the ten weeds we record in crested dogstail are 



common throughout Ireland. It has been our duty from time to time to 



report that certain samples contained weed-seeds which indicated that the 



samples were not genuine. Red clover, e.g., with American weeds in it, has 



been put on the market as English. Thanks to the publication of Stebler's 



paper, it will be possible to develop this necessary detective work. 



Fortunately, Dr. Stebler let us have for the Station " eine reclit schone 



Sammlung " (as he called it) of both indicator-weeds and their seeds, 



and these have been of the greatest help in the work described in this 



paper. 



In books on systematic botany, as in the standard works on the Irish 

 flora, attention is always called to the standing of a species recorded. 

 Thus, it is described as either indigenous or introduced by man. The flora 

 of Ireland is essentially a derived, selective one, being mainly British in 

 origin. 



The term " alien " is useful as applied to a species known to have been 

 introduced within historic times, or clearly of foreign origin, though now it 

 may be self-sowing, and quite as much at home as a na,tive species. 



The terms " alien " and " casual " are more or less synonymous. It 

 would tend to clearness if " casual " stood for an alien not yet known to be 

 capable of self-sowing. 



Colgan states, in his " Flora of County Dublin," that of the 750 species 



