136 GROWTH AND WORK OF PLANTS 



growths are haustoria, or suckers, because they attach the vine 

 to its host and serve as absorbent organs. There are fibro-vascu- 

 lar bundles (paragraph 98) in the haustoria which connect with 

 those of the vine and also form an intimate connection with those 

 of the host. Through these haustoria the dodder absorbs 

 solutions of mineral substances, and also of carbohydrates and 

 protein manufactured by its host. Receiving these food sub- 

 stances already prepared the parasite has no need of chlorophyll 

 nor of expanded leaves. In accordance with the general law, 

 therefore, that when an organ ceases to function it becomes re- 

 duced or discarded, the leaves of the dodder have become reduced 

 to mere scales on the stem, and the root dies as soon as the vine 

 becomes attached to its host by the haustoria. The vine and its 

 scale leaves are pale yellowish in color. 



212. Nutrition of the mistletoe (Phoradendron flaves- 

 cens). The mistletoe is a well-known plant especially in the 

 southern half of the United States, and is often used farther north 

 in Christmas decorations. It is a parasite on a number of trees, 

 especially on red maple and the tupelo, but occurs on the oaks 

 and some other trees. It is a small branched shrub often forming 

 dense tufts on the branches of its host. It is very conspicuous in 

 winter because it holds its leaves while its hosts are bare, and 

 because of its green stems. Having chlorophyll it can manu- 

 facture its own carbohydrates. Its roots penetrate the branches 

 of the trees on which it grows, and it derives its mineral foods 

 and water from its host. 



213. Other parasitic flowering plants are the beech drops 

 (Epiphegus) growing attached to the roots of beech trees, the 

 small mistletoe (Arceuthobium) attached to twigs and branches of 

 the native spruce. The mistletoe of Europe (Viscum album) 

 grows on a great variety of trees, but develops more freely and 

 luxuriantly on apple trees, the black poplar and certain spruces, 

 trees which have a soft cortex, while it is rarer on the beech, birch, 

 etc. It becomes a great pest sometimes in apple orchards, and 

 the farmers are said to welcome the collectors who gather it for 

 Christmas "greens." 



