200 
POPULAR SCIENCE REVIEW. 
The mistletoe is the only green parasite in this country ; and 
often forms a conspicuous feature in the physiognomy of 
vegetation on the leafless trees of winter. It chiefly abounds 
on the apple, the pear, and plum tree ; and I have also seen 
it on the poplar. Some authors say it grows on the silver-fir 
tree; but instances of its attacking the Coniferce are very 
rare. Occasionally it may be met with on the oak, but its 
very unusual presence on this tree has probably much to do 
with the peculiar reverence with which plants found in this 
situation were regarded by our early ancestors, and their priestly 
advisers the Druids. In warmer countries, where the Loranthus 
grows, its scarlet flowers form a most brilliant contrast to the 
dark green leaves of the plant by which it is supported. In 
Chili a leafless Loranthus covers with a scarlet carpet a large 
candelabra-like cactus, whose snow-white flowers, eight or nine 
inches long, project from it, and present a beautiful object to 
the eye. 
Parasitical plants, properly so called, are very numerous in 
the vegetable kingdom, although the species of Loranthus and 
Viscum alone have green leaves. There are parasites which 
live externally on their victims ; others which are insidiously 
introduced into the interior, where they flourish until they pierce 
through the skin, come in contact with the air, and disseminate 
themselves. These are known by the various names of mildew, 
rust, smut, brand, &c. Those which attack externally assume 
different forms, and have either ordinary green leaves, as in 
the mistletoe, or brown scales and colourless stems. The 
brown scaly parasites attack the roots of plants, and their 
underground habits have caused them to be little examined. 
The most common species in Europe are the various kinds of 
Orohanche, broom rape, which attack hemp, clover, lucerne, and 
many other plants ; and the species of Monotrojpa, birdsnest 
orchis, and Lathrcea, tooth- wort, which infest the roots of the 
beech, the fir, and the ash. The best account of the manner 
of growth in brown parasites is given by Mr. Bowman, who 
studied with care the habits of the Lathrcea squamciria. 
One of the most remarkable peculiarities of such plants is 
the constant absence of all green colour, though exposed to 
the strongest fight. Connected with this is another curious 
property, that of resisting the attraction of light, towards 
which all the green parts of a plant irresistibly turn. 
The Dodders also are true parasites, although they do not, like 
the mistletoe, plunge their roots into the wood and incorporate 
themselves with the tissue of another plant. Yet they twine 
themselves around the branches of trees, and send out suckers, 
which, becoming firmly attached to the bark, attract a suf- 
ficient amount of nutriment to support their tissue. 
