264 COMMON WEEDS 



O. minor Sutt., or Lesser Broom-rape, is the chief 

 trouble of the farmer, chiefly attacking clover, and 

 occasionally doing great damage. This pest (Fig. 73) 

 is parasitic on a number of plants, however, and is 

 recorded by Kirchner as occurring on Trifolium pratense y 

 T. repens, T. hybridum, T. incarnatum, Lotus corniculatus, 

 and other plants. Sorauer says it is so harmful to 

 clover in Baden that it has received the name of 

 " clover devil " (kleeteufel). In Britain it occurs from 

 the Border counties southwards ; the stem is 6 inches 

 to 2 feet in height, rather slender compared with some 

 other species ; and the flowers, appearing from June 

 to October, are 1 inch long, reddish, brown, violet, 

 purplish, or yellowish-brown in colour, many being 

 crowded in a long spike. 



O. Rapum-genistce Thuill., or Larger Broom-rape, 

 occurs from Dumfries southwards, in Ireland, and in 

 the Channel Islands, and is parasitic on the roots of a 

 few shrubby leguminous plants, as Gorse and Broom. 

 It is brownish in colour, with flowers, about i inch 

 in length, of a yellow and purplish tint. The flowers, 

 which are in dense spikes, appear between June and 

 August. 



O. ramosa L. infests hemp, and on the Continent 

 tobacco, while it has been recorded on maize (Nobbe). 

 It is brownish or pale yellow in colour, with light blue 

 or white flowers. 



Several other species of Broom-rape are found in 

 Britain, but are of little agricultural importance. 



The seeds of Broom-rapes are very minute, almost 

 dust-like, and are produced in large numbers in two- 

 valved capsules, and it has been stated that ten million 

 seeds weigh i gram. Sorauer quotes Wentz as having 

 seen 70 to 90 seed-capsules, containing on an average 

 1500 seeds, , on a single plant! These minute, light 



