"Curly grain" refers to the figure of circlets and islets and contours, often of great beauty, caused by cutting a flat surface in crooked-grained wood. See Fig. 27, curly long-leaf pine, and Fig. 28, yellow poplar. When such crookedness is fine and the fibers are contorted and, as it were, crowded out of place, as is common in and near the roots of trees, the effect is called "burl," Fig. 29. The term burl is also used to designate knots and knobs on tree trunks, Fig. 31. Burl is used chiefly in veneers.
Fig. 27.
Curly Grained Long-leaf Pine (full size).
Fig. 28.
Curly Yellow Poplar (full size).
Irregularity of grain is often caused by the presence of adventitious and dormant buds, which may be plainly seen as little knobs on the surface of some trees under the bark. In most trees, these irregularities are soon buried and smoothed over by the successive annual layers of wood, but in some woods there is a tendency to preserve the irregularities. On slash (tangent) boards of such wood, a great number of little circlets appear, giving a beautiful grain, as in "Bird's-eye maple," Fig. 30. These markings are found to predominate in the inner part of the tree. This is not at all a distinct variety of maple, as is sometimes supposed, but the common variety, in which the phenomenon frequently appears. Logs of great value, having bird's-eyes, have often unsuspectingly been chopped up for fire wood.
