88 



Lucerne and Trefoil Seed. 



[may, 



houses of repute, and paying a fair price, has, in a degree, 

 a guarantee of freedom from dodder and other objectionable 

 impurities. It is sometimes difficult to recognise the seeds 

 ©f dodder in a sample of clover or lucerne. The colour of the 

 dodder seeds varies from a dark yellow to a light grey or brown, 

 while the surface is dull and somewhat rough or pitted. In some 

 cases it is impossible from appearance to say whether one is 

 looking at a seed or at a small spherical pellet of soil, until one 

 presses gently the suspected seed under the blade of a knife ; if 

 it is soil it crumbles into pieces, if a seed it may, under microscopic 

 examination, prove to be dodder (Fig. 5). 



The seed supply of lucerne is mainly, if not entirely, from the 

 continents of Europe and America, and unquestionably the best 

 and purest seed offered in this country is giown in France, in the 

 district of Provence. 



Some of the impurities common to lucerne are Bokhara clover 

 {Melilottts alba), Polygonum aviculare (knotgrass), Ruviex crispus 

 (curled dock), Helniinthia ecJiioides (ox-tongue), and Centaurea 

 solstitialis (yellow centaurea), the two latter being frequently 

 found in French seed ; other im.purities commonly met with are 

 Plantago lanceolata (rib grass), Ruinex acetosella (sheep's sorrel), 

 Chenopodiuin album (goose-foot). When seeds of lucerne are 

 analysed they should be closely scrutinized for Bokhara clover, as 

 this is an undesirable plant, even in very small quantities, on 

 account of its poor quality as a forage crop and its unsightly wiry 

 growth towering high above the lucerne. When Bokhara clover 

 is mixed with lucerne it becomes a matter of judgment and ex- 

 perience to detect it readily. The colour of individual seeds k 

 uniform throughout — yellowish-brown or yellow tinged with 

 green, the former colour mostly predominating in samples of 

 Bokhara. The micro-photograph of Bokhara clover (Fig. 6) 

 shows its slightly varied form. The shape is oval-oblong, and 

 the sides, as can be seen, are slightly depressed or flattened, 

 the faint groove indicating the position of the radicle. 



The seeds of trefoil {Medicago lupulina) are also found in 

 lucerne, and on account of the colour and size of the grains they 

 may easily be overlooked unless closely examined. 



The purity of good commercial seed should be high — at least 

 96 per cent. pure. In the best seed 98 per cent, or 99 per cent. 



