CLIMBING PARASITES. GREEN-LEAVED PARASITES. TOOTHWORT. 



173 



not take place at either extremity, but always in the median part of the filament. 

 It is so rapid that by the fifth day after the commencement of germination the 

 entire seedling has increased fourfold in length. As early as the third day 

 after the emergence of the tip that fastens itself in the earth, the integument of 

 the seed, which until then continues to envelop the opposite extremity, is thrown 

 off and the seedling's apex is exposed. The reserve-food, given by the parent- 

 plant to the seedling as provision for the journey, has meanwhile been absorbed 

 and consumed, so that the seedling is now thrown entirely upon its own resources, 

 and depends for sustenance upon the earth, to which it is firmly attached, and upon 

 the surrounding air. Having no chlorophyll, it is not in a position to take up 



-*£ 



x- 



MtH £•& 





'»».fi 



Tig. 34.— Seedlings of Parasitic Plants. 



' te 



7S 



i. z, 3, t, s, 6 The Great Dodder (Cuscuta Europcea). '■ a. a- 1°. "• ' 2 A Broom-rape (Orobanche Epithymwri). 

 w. 14, ie Wood Cow-wheat (Mela/mpyrwm gylvaticum). 



materials from the air; nor can it derive sufficient nutriment from the earth, even 

 supposing that water is imbibed by the cells of the clavate extremity. There is no 

 doubt that it now grows at the expense of the substances contained in the cells of 

 this club-shaped end. The latter at once begins to shrivel and soon dies, whilst 

 the upper part of the filament elongates conspicuously. Should this portion of the 

 seedling meantime come into contact with a neighbouring plant, a rigid haulm, 

 or anything else that will serve as a support, it straightway coils itself round the 

 object in question, and its future is then, as a rule, assured. 



Failing such a support, the seedling, after the death of the clavate extremity, 

 falls down and sinks to the ground. In doing so, it almost invariably touches 

 an adjoining object, whereupon it immediately winds tendril-like round the 

 support thus afforded. But if there is nothing anywhere around to serve as 

 a prop, and the young seedling, by this time from 1 to 2 centimeters long, 

 comes to rest upon the bare earth, all further growth is stopped. It preserves 

 its vitality, however, for a surprisingly long time, and may remain almost unal- 



