94 WEEDS OF FARM LAND 



(C. epilinwri) seems to live entirely on flax ; lesser dodder (C. 

 epithytnuni) on the roots of heath, thyme, and other small 

 shrubby plants, while the common or greater dodder (C. 

 europad) is much less exclusive and is found on a great 

 variety of plants in Europe and parts of Asia. 



The seeds of dodder fall to the ground or are sown along 

 with a crop. They start into growth, each seedling develops 

 a small root and sends up a thin delicate stem into the air. 

 This stem twists round seeking for a congenial host, but if 

 this is not found the seedling dies. If a host is available the 

 dodder twists round it and rapidly fastens itself on to the stem 

 by means of suckers ; when connection is established the 

 roots and the lower part of the stem of the dodder die away, 

 leaving the parasite disconnected from the ground and entirely 

 dependent upon the host for its food. 



The suckers are small swellings or tubercles resembling the 

 beginnings of roots. They gradually bore their way through 

 the epidermis or outer skin of the host plant, then through the 

 underlying soft tissue or cortex until they reach the central 

 part of the stem. Intimate connection is thus established 

 between the conducting strands of the host plant and those 

 of the dodder, so that a clear passage is available for the 

 transference of food in a ready prepared condition from the 

 host to the parasite. If much dodder is present the drain on 

 the resources of the host is often so severe that the victim 

 cannot stand the strain but dies of starvation, and in this way 

 large areas of clover are often ruined. Dodder is recognised 

 as one of the most dangerous foes of this crop, and therefore 

 legislation is adopted against it, making it an offence to sell 

 crop seed contaminated with dodder seed. 



Although most species of dodder are usually associated 

 with one or more well-defined host plants, it is now found that 

 some of them are capable of infecting other plants, including 

 various kinds of weeds. This renders the pest still more 

 dangerous, for dodder, being under favourable circumstances, 

 is often able to pass safely through the winter in the vegetative 

 condition and may succeed in escaping observation on the other 

 hosts even when the main crop has been drastically dealt with. 

 The clover dodder (Cuscuta trifolii) has been known to spread 

 on to hoary plantain and bedstraw, the common dodder will 

 spread from nettles to grasses, 1 and another species (Cuscuta 



1 Montcmartini, L. (1913), Alcune malattie nuove o rare, Rivista di 

 Patologia vegetale, VI, pp. 204-210. 



