No. 493] THE PHENOGAMOUS PARASITES 



31 



times sessile and sometimes having a short stem, issues 

 from the host at the place of entrance of the embryo. The 

 parasitism is complete. 



Examples: The rafflesias and related forms. 



One of the most remarkable characteristics of group VI 

 is that the individual plants of many of its species reach 

 the lowest structural limit of the phenogam. That is, 

 each one of such plants consists of a single flower which 

 is sessile upon the bark of the host, or apparently some- 

 times npon its cambium laver. In other cases the nlant 

 consists of a short, 

 single scaly stem be- 

 sides the flower. The 

 sessile species are ex- 

 amples of flowering 

 plants reduced to the 

 flower alone, assum- 

 ing that the haus- 

 torial processes at its 

 base represent the 

 torus, as they seem to 

 do. While the nor- 



whieh arc' necessary t 

 ing flower and fruit, the sessile Rafflesias throw the re- 

 sponsibility of all else upon the host and furnish only 

 the reproductive organs for their own perpetuation. 

 They serve that purpose effectively, however, although 

 they are rootless, stemless, branchless and leafless plants. 

 And yet they are no more lacking in vitality than are the 

 most vigorous members of the vegetable kingdom. 



Although the seeds of Eafflesia, like those of the mistle- 

 toes, germinate upon the bark of a woody host, their em- 

 bryo is not of normal structure, as is that of the mistletoes, 

 but is simple and filiform, as is that of groups IV, V, 

 and VII. Because the embryo of Eafflesia is not differ- 

 entiated, and therefore has not a true radicle; and because 

 it is not able to germinate upon the ground, it is assumed 

 that the protruding end of its offshoot does not represent 



