THE MISTLETOE FAMILY 



133 



Fig-. 122. — A young 

 Mistletoe {Vis cum alburn),^ 

 the roots being' laid bare. 



are covered by new layers of wood, so that, in course of time, 

 the roots of the parasite appear to be in the very centre of the 

 branch and* to be fused with the wood tissue of the host. Now, 



the woody tissue of a tree is the channel 

 for the ascending sap (see II. Part, Stem). 

 And it is, therefore, the ascending water 

 and its mineral ingredients which the 

 Loranthus takes from the host. Other 

 nourishing substances, such as sugar, starch, 

 albumen, are conducted in vessels that 

 are in the inner bark of the tree. The 

 Loranthus does not feed upon them, hut 

 prepares them by itself. And for this 

 purpose it requires green leaves like other 

 plants. The Loranthus may, therefore, be 

 called a Water-Parasite. 



Notwithstanding this fact, the Loranthus 

 destroys the host. As we have seen, it interferes with the flow 

 of sap in the woody tissue of the host. Accordingly the host is 

 weakened, and not infrequently the branch is killed by the in- 

 truder. If the parasitic bush is only cut off, the roots lying in 

 the tissue of the host will sprout again. The only remedy to 

 save the tree is to cut oft' the branch below the place where it is 

 attacked. 



Many other parasites feed not only on the ascending sap of their 

 hosts, but grow entirely at their expense, taking water, starch, nitro- 

 genous and every other kind of food they require from their host. 

 Such plants need no longer develop any organs to absorb raw food 

 from the air and, therefore, dispense with leaves. In Cassytha (page 

 130) we have met with such a holoparasite*. 



On the other hand there is still another categorj^ of parasites 

 which we may call hemiparasites'\ of which the Sandalwood tree, 

 Santalum album {Kan. Srigandha mara; Mai. Candana maram), is 

 an example. This tree has roots of its own in the ground and deve- 

 lops green foliage like ordinary trees. Yet it is a parasite. When 

 its roots come into contact with roots of other plants, they attack 

 them and suck food from them. This explains a curious fact which 



*From Greek holos, whole. 



fFrom Greek hemi, half. 



