Page:The Oak.djvu/173

 Rh Of other animals which injure oaks I may mention the various cattle, which bite off or rub the bark and buds; hares, squirrels, mice, etc., which nibble roots and buds and destroy the acorns, etc.; and a few birds; and certain beetles, which bore into the wood.

Among the pests belonging to the vegetable kingdom the following may be selected from a large number: The honeysuckle occasionally twists tightly round the young stem, and in course of time so compresses the cortex that the formative materials from the leaf-crown have to pass in a spiral course between the coils of the strangling plant, and the tightly-squeezed parts may be starved as the tree thickens, and even the death of the cambium may follow, especially if one or two of the honeysuckle coils come to lie nearly horizontally round the stem.

As a rare event the mistletoe is found on the oak. A much commoner parasite of the same family is Loranthus europœus, which does considerable damage to oaks in some parts of Europe. The sticky seeds are carried into the trees by thrushes. Here they germinate, and send their roots, or haustorial strands, into the cortex of a branch as far as the cambium, where they spread and feed on the contents of the young wood- and cambium-cells, causing malformations of the injured branch at the spot attacked, owing to the hypertrophy of the tissues, to which abnormal quantities of food materials now flow (Fig. 41); and frequently bringing about the death of the upper parts of the branches owing to the