[ 446 i 



XXXIII. 



AGRICULTURAL SEEDS AND THEIR WEED IMPURITIES: 

 A SOURCE OF IRELAND'S ALIEN FLORA. 



By T. JOHNSON, D.Sc, F.L.S., 

 Professor of Botany in the Royal College of Science, Dublin ; 



AND 



MISS R. HENSMAN. 

 (Plates XXII., XXIII.) 



[Read March 22, 1910. Received for Publication Apiul 12. Published July 22, 1910.] 



Members of the Royal Dublin Society have been for years in a position to 

 have seeds tested by the Society's Consulting Botanist ; and, in the year 

 1899, one of us (T. J.) undertook to report on the germinating power of 

 certain clover and grass seeds for the Congested Districts Board. But it was 

 not until the year 1900, when the Department of Agriculture and Technical 

 Instruction for Ireland started the first and still tlie only official Seed-testing 

 Station in the United Kingdom (charging farmers Sc^. and seedsmen 3s. — now 

 2s, — for a full report on each sample), that seed-testing on an extensive scale 

 was carried out in Ireland. We have been in charge of the work (1) of the 

 Station from the first, beginning with an investigation of the flax-seed 

 supply. During the period 1900-1909 inclusive, Reports have been made on 

 the genuineness, purity, and germinating power of 11,000 samples, the 

 yearly average being now more than 2000. The following Tables (p. 447) 

 show the average germinating percentage of these samples. 



The results obtained by testing seeds of the same species in the well-known 

 Ziirich Station (2) and by the twenty-one different Grerman Stations (3) are 

 incorporated for comparison in Table II. 



The Tables show apparently that tiie seeds bought and sown by the 

 farmers in Ireland have in many cases a lower germinating power than those 

 sown by the farmers abroad. The Department's Station, as stated in the 

 first annual Report, difliers from all others in that, while giving separate 

 reports on the purity and germinating percentage of the seed, it submits to 

 the germination tests, seeds which, though complete in outward appearance, 

 may be without a kernel, i.e. " chaff." Such seeds are treated as impurities in 

 other Stations. 



