Page:Popular Science Monthly Volume 85.djvu/424

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 Quercus lobata Owing to the washing away of the bank the tree has lost a portion of its former support and has leaned toward the streamway. The generalized character of the root system is fairly well shown.

the usual type, in that there is large development of the tap-root, from which extend at various depths large laterals in comparatively large numbers. The secondary roots may also penetrate fairly deep, although occasionally they lie near the surface also. In large specimens, superficial roots as long as 70 feet have been observed. Secondary roots usually branch relatively little. In a word, the root-system of the roble oak is especially well adjusted to take advantage of the more deeply-lying soil moisture, while at the same time the more superficially placed roots can absorb water from the more superficial soil layers. As will be shown below, the root habit of the plant is one well calculated to close adjustment with the peculiar habitat frequented by the species.

The root-system of the encina oak is characterized by an especially well-developed superficial portion, which consists of numerous relatively short and relatively slender roots, which are placed, for the most part, within three feet of the surface of the soil. There are also more deeply penetrating roots, but these are relatively few in number. In young