The swellings which affect the trunk or branches are due to the irritation of the fungus mycelium, which is perennial and stimulates the wood and bark to abnormal growth. These swellings become fissured and are entered by the spores of other fungi, which rot the wood; and the tree, if the stem is affected, is often broken off at the weakened spot by storms or falls of snow. The witches’ brooms begin as young shoots, bearing small yellowish leaves, on the under surface of which two rows of ecidia are developed in August. These shed their spores at the end of that month and the leaves soon afterwards die and fall off. The affected shoots keep on growing, and develop into peculiar growths, set upright generally on the branches, and consisting of numerous twigs anastomosed together. The fungus passes one stage of its life on various species of Stellaria, Cerastium, and their allies, and Fischer! recommends the extirpation of these plants from nurseries in which the silver fir is raised.
The silver fir is very liable in its native forests to be attacked by the mistletoe. Modified roots, the so-called sinkers of the parasite, have been found in the wood enclosed in forty annual rings and as much as 4 inches long, showing that mistletoe may live on the tree for forty years. When the mistletoe dies the rootlets and sinkers survive for a time, but finally moulder and fall to pieces. The affected parts of the wood show numerous perforations, and exactly resemble the wood of a target that has been penetrated by shot or small bullets.’
The bark of the silver fir remains alive on the surface to an advanced age ; and, on this account, when branches, stems, or roots of adjoining trees get into contact, they often become grafted together. This is the explanation of the curious phenomenon of the vitality of the stumps of certain trees in forests. After the stem is cut down, these stumps continue to increase in size and produce a callosity, which eventually covers the stump in the form of a hemispherical cap. Such a stump procures its nourishment from an adjoining tree, with which its roots have become grafted.’
Cultivation
The silver fir* was introduced into England about the beginning of the seventeenth century; but the exact date is uncertain. The earliest trees recorded are two mentioned by Evelyn,’ which were planted in 1603 by Serjeant Newdigate in Harefield Park in Middlesex. These had attained about 80 feet high in 1679, but from inquiries made by the late Dr. Masters, there is no doubt that they have long since been cut down.
Though in its own country the silver fir is a tree of the mountains, yet it attains its greatest perfection in the south and west of England, Scotland, and
1 Abstract of Fischer’s paper in Journ. Roy. Hort. Soc. xxvii. 272 (1902).
2 See Kerner, Nat. Hist. Plants, Eng. trans. i. 210, fig. 48 (1898). We have never seen or heard of mistletoe on the silver fir in this country.
3 See Mathieu, Flore Forestière, 529 (1897).
4 Staves were found, in 1900, lining the ancient wells in the Roman city of Silchester, Hants; and the wood was identified by Marshall Ward with A. pectinata. The casks, from which the staves had been taken, were probably imported from the region of the Pyrenees, and had either contained wine or Samian ware. Cf. Clement Reid, in Archaeologia, lvii. 253, 256 (1901).
5 Sylva, 106 (1679).
