MISTLETOE. 55 



(embryos) thrown from a Jeffrey pine onto a twig 

 of an oak standing beneath it can germinate, but can 

 not penetrate the bark and enter the living tissue. The 

 same seed landing on a young Jeffrey pine twig, how- 

 ever, develops a small rootlet, which perforates the 

 bark. From this rootlet are developed other roots (cor- 

 tical roots) running up and down in the bark of the 

 twig, and from these again so-called sinkers are 

 started that is, roots growing straight down to the 

 wood. In the meantime, the mistletoe plant develops 

 on the outside of the twig at the cost of the host tree. 



The damage the mistletoes of both groups cause to 

 their host consists less in depreciation of timber than 

 in the attack on the vital organs of the host. They 

 belong to the higher plants which are characterized by 

 roots, stems, green foliage, and flowers. Parasitic life 

 has robbed the mistletoes of their independence. They 

 are unable to take raw food from the soil; their root 

 system is much reduced and has adapted itself to the 

 function of tapping the tissues of their hosts. The 

 foliage of the Razoumofskyas is reduced to small scales 

 and they contain very little green pigment (se p. 9) 

 with which to assimilate carbon dioxide from the air. 

 They depend, therefore, upon their host not only for 

 water, but also for the greater part of elaborated food. 

 The Phoradendrons, on the other hand, generally 

 possess green leaves, or, at least, green stems. They 

 elaborate their own food and normally draw only water 

 and raw food from the host. 



The effect of the mistletoe on its host is chiefly that 

 of a parasite tapping the saps and girdling the, branch 



