i;6 



Broom-Rape. 



[JUNE, 



quirements of the root crops have been satisfied is probably 

 best given to the young seeds in the early winter, to act both as 

 a fertiliser and as a mulch. The seeds benefit greatly, and at 

 the same time much of the added fertility is retained for the 

 corn crop that follows ; manuring the young seeds is certainly 

 preferable to manuring the old ley before it is ploughed up for 

 wheat or oats. A certain amount of the farmyard manure 

 made on the farm should, however, always be reserved for the 

 meadow land, especially on light soils and on land compara- 

 tively newly laid down to grass. Of course, dung would be 

 wasted on rich grazing land ; it is the thin light soils that are 

 cut for hay, or grass land that has only been laid down for a 

 few years and has had no time to accumulate a stock of humus, 

 which are most benefited by an occasional dressing of farm- 

 yard manure — once in every four or five years. 



BROOM-RAPE. 



Amongst plants which are usually classed as weeds — not 

 merely because they are " out of place " but because they 

 are harmful or of no value — there are several which are para- 

 sitic in character, and for certain reasons of an insidious 

 nature. In a previous number of this Journal some account 

 has been given of the parasite Dodder,* and it is now proposed 

 to deal with another plant pest known as Broom-rape. 

 Although it is perhaps of less economic importance than 

 dodder, yet in some districts the broom-rape which attacks 

 the clover crop may be the cause of much loss. Several species 

 are harmful to other plants, and the more important of these 

 will here be described. 



Description of Broom-rapes. — The broom-rapes are included 

 botanically under the order Orobanchaceae, of w r hich there are 

 ii genera, and according to Bentham and Hooker 150 species; 

 of these about 100 are members of the genus Orobanche (or broom- 

 rapes). Few of them, however, occur in the British Islands. 

 These plants are annual, leafless, brownish root-parasites, 

 containing no chlorophyll or green colouring matter. The 

 base of the stem is somewhat tuberous and scaly ; the stems 

 are generally stout and scaly, and usually occur singly ; while the 



* Journal, September, 1906, p. 331. 



