646 FARM ' SEEDS ' : SPECIAL 



and viewed in front of the micropyle, the seed has a bent 

 appearance, the radicle not lying in the same plane as the 

 cotyledons, but usually curved a little to one side. 



The length of a seed varies from 2-5 to 3 mm.; width about 

 I '5 mm.; and thickness a little over i mm. 



Colour and Brightness. — The colour is a pale buff-yellow 

 in fresh seeds ; when old they darken to a yellowish brown. The 

 surface is much duller than that of any similar seeds of allied 

 plants. 



Purity. — The purity of lucerne should be high, about 96-98 

 per cent. The most commonly occurring impurity, and one 

 which is to be specially looked for, is Trefoil {Medicago lupulina 

 L.), the seeds of which in colour and size resemble those of 

 lucerne (see Fig. 196), but are only about one quarter the 

 price. 



' Bokhara Clover ' {Meliloius albus Desr. and Medicago 

 maculata Willd.) seeds occur in some adulterated samples. The 

 former seed gives a smell of new-mown hay to the sample, due 

 to a small amount of coumarin present in it. The latter is a 

 larger seed, with a darker micropyle than lucerne, and the 

 radicle reaches only about half the length of the seed. Seeds of 

 clover dodder {Cuscuta trifolii Bab.) and the larger Cuscuta 

 racemosa are also met with. 



Germination Capacity. — In the finest samples this is about 

 98 per cent., and anything lower than 90 per cent should be 

 avoided. The number of hard seeds averages about 10 per cent. 



Weight. — 1000 seeds should weigh 2 grams. Bushel-weight 

 64 lbs. 



Yellow Trefoil, ' Nonsuch ' Clover, or Black Medick 

 {Medicago lupulina L.). — The true seeds are sown, but usually 

 the black fruits with characteristic curved lines upon them, and 

 containing one seed, are present in samples. 



Form and Size. — These seeds are usually smaller than those of 

 lucerne, and can be separated from the latter by means of the 



