PLANTS AS DISEASE PRODUCERS 



305 



of chlorophyll and whose seeds sprout in the soil and send up a filiform 

 stem which brings itself by its movements into contact with some 

 host plant, which is penetrated by parasitic roots which enter, as 

 far as the bast region and extract elaborated food. When estabUshed 

 on the host the parasite severs its soil connection. Leaves have been 



Fig. 122.- 



-Dodder (Cuscuta) in flower and parasitic on a golden rod, Solidago ulmi- 

 folia. (From Gager, after Elsie M. Kitiredge.) 



reduced to a few scales located near the clusters of small flowers and the 

 twining stem assumes a yellow, or orange-yellow color. The dodder, 

 Cuscuta (Figs. 122 and 123-), belonging to the bindweed family, is 

 illustrative of these parasites. 



Related in habit are species of the genus Cassytha. Most of the 

 species of Cassytha inhabit Australia, but some are found in New 

 Zealand, Borneo, Java, Ceylon, the Philippines, the Moluccas, South 



