TAIIASIXISM IN ^LA:^fTS AND ANIMALS. 283 



tion, the leaves have become leathery and inactive, while at the 

 same time rootlets are developed v^^hich suck up nutritive j uices 

 to the great detriment of the supporting tree. 



But there is an interesting group of plants vi^hich, while not 

 parasitic, have yet taken on something of the habit of parasites 

 in deriving their support from organic matter instead of from the 

 air and the earth, like ordinary vegetables. These go by the 

 name of "saprophytes," and comprise such " carnivorous" plants 

 as the sundews and butterworts, which live largely upon insects 

 caught by the viscid secretions of their leaves. Here also we 

 may recognize degenerate structure in a scarcity of green colour- 

 ing and poorly developed roots. Fungi form, so far as mode of 

 nutrition goes, a closely allied group. 



Among truly parasitic plants there are none more interesting 

 or, in this country, more familiar than the Broom-rapes {Oro- 

 hanche) and the Dodders {Cuscuta). The Broom-rapes grow ex- 

 clusively upon the roots of certain shrubs or herbaceous plants 

 such as the Broom, Whin, Ivy, etc., pushing up through the 

 earth, brown, withered-looking flower-spikes, which are beset 

 with scales instead of ordinary leaves. The Dodders are very 

 different in habit, entwining their thread-like, wandering stems 

 often in very rampant fashion about furze-bushes, clover, and 

 other plants — the threads being festooned with beautiful little 

 bosses of flesh-coloured or greyish bloom. In this way the para- 

 site lives entirely detached from the earth and drawing its 

 nourishment from the supporting shrub. Its mode of growth is 

 said to be this : — the seeds of the two plants, host and parasite, 

 ripen together, fall into the soil and germinate. Should the 

 young Dodder begin its growth beyond reach of a host its exist- 

 ence soon comes to an end, but if in contact with a host it sends 

 out rudimentary roots or " haustoria" which penetrate the tis- 

 sues of the larger plant and provide it with the nourishment 

 necessary for its continued growth. Other interesting examples 

 of plants now known to be at any rate partly parasitic are the 

 Yellow Battle {Ehmanthus Crista-galli), the Eye Bright {JEu- 

 phrasia officinalis)^ and the Bed Battles or Louse worts {Pedicu- 

 laris palusirts and P. arvensis). These grow upon the roots of 



