] 26 THE CLOVER CROP. 



cient, and the clover plants, if not already too much 

 injured by the parasite, soon resume their vigour, and the 

 bare and blackened spot disappears. This is a simple and 

 inexpensive remedy, and well deserves a trial. At the 

 same time, it is always more desirable to prevent than to 

 cure ; and this may be materially secured by a little atten- 

 tion to the seed, if, on examination, any doubts exist as 

 to its purity and freedom from dodder. The seed of the 

 latter differs in colour, size, and shape from the clovers, 

 being of a grayish colour, but little more than half the size, 

 and spheroidal, or rather like the divisions of the orange 

 in shape. A "No. 17 sieve/' Dr. Lindley tells us, will 

 allow the dodder seed to pass through, and will detain 

 both clover and lucerne seed. 



The clover plants are also liable to great injuries from 

 another class of parasitical plants, which differ in their 

 mode of attack from the dodder, which latter attaches 

 itself to the stem above the surface, while these con- 

 fine themselves to the roots of the plant. Foremost 

 amongst these are the "broom rapes" the Orobanche 

 major and 0. minor a class of herbaceous leafless plants 

 growing parasitically upon the roots of other species, 

 the two members specified confining themselves chiefly 

 to clover and allied genera of leguminous plants. The 

 habit of the "broom rapes" is to attach themselves to the 

 end of the roots ; the latter then swell and form an enlarge- 

 ment, which serves as a base from which the parasites 

 can draw their supplies of food from the circulation of the 

 plant they have fixed themselves upon. It is most pro- 

 bable that the seeds of these plants are also sown down 

 with the clover. They differ, however, greatly from 

 them in appearance, being of a grayish colour, and less 

 plump and smooth in the skin; and as they are much 

 smaller in size, they can readily be distinguished and 

 separated by using a sieve of the size given above. 



