201 



This species being thus unable to manufacture for itself the 

 carbonaceous organic food materials which it requires is obliged 

 to obtain them ready-made from other plants. If the soil is 

 carefully removed from the roots of an Orobanche plant these are 

 found to be joined to, and in intimate connection with, 

 the roots of the neighbouring Jmustard plants from~which they 

 take their necessary food materials. 



175. This is the well-known (2) Cuscvta 



leafless Dodder, masses of whose wire-like stems may often be seen re ft exa ' 

 enveloping trees and shrubs with a yellow, or greenish, 

 mantle. Although the plant contains a little chlorophyll, 



this is quite insufficient for the manufacture of the food 

 it requires. If we examine the twining stem we find that, 

 where it comes in contact with the stem or twigs of the 

 host, small wart-like protuberances are developed which 

 pass into and are in intimate connection with the tissues of 

 the host from which it derives its water and nourishment. 

 These suckers, or haustoria, are able to force their way into the 

 tissues of the host without difficulty, partly owing to the action 

 of dissolving enzymes which their filaments excrete after the 

 manner of fungal hyphae. The seed of this species germinates 

 on the ground, but the rootlet which is developed soon dies off, 

 and if the filamentous stem fails to encounter a suitable host 

 the seedling perishes. If allowed to develop undisturbed 

 the Dodder may kill the plant attacked, and gaps in garden 

 hedges caused by it may often be seen. 



176. This very common plant ( 3 ) L <" anthu3 



. , f . , i P ji longiftorus. 



may be taken as iairly typical ot the numerous species 

 of Loranthus and Viscwn which occur in Indian forests. 

 Their chief peculiarity consists in the fact that they pos- 

 sess a considerable supply of chlorophyll, many of them, like 

 our example, being provided with well-developed green leaves. 

 This plant appears to be chiefly distributed by birds who 

 deposit the seeds on the branches and stems of trees where 

 they germinate and grow. The young radicle, piercing through 

 the cortex of the branch or stem attacked, penetrates to the 

 young wood, in the tissues of which it spreads and develops. 

 This plant obtains its supplies of water and mineral salts 

 directly from the wood elements of its host and the portion of 

 the branch or stem above the point of attachment of the para* 

 site, being deprived of its water-supply, dies and we get stag- 

 headed trees. The attacked branches become swollen and dis- 

 figured while the parasitic roots, being embedded in the wood, 



