Spiral Grain in <i>Pinus Oocarpa</i>

Authors

  • Dana Houkal

Keywords:

Pinus oocarpa, spiral grain, interlocking grain

Abstract

Patterns of spiral grain in twenty trees of Pinus oocarpa Schiede growing in the central highlands of Honduras were examined. The mean slope of fibers in the stem was 4.1°, with a range from 0° to 16°. In 84% of the samples measured, grain deviation was right-handed. Left-handed deviations were observed in 10% of the samples and only 6% were straight-grained. Large among-tree differences in grain direction and magnitude were found, and within-tree variation was high in both radial and horizontal directions for most individuals. Notwithstanding the large variation, a general within-tree pattern of spiral grain was detected in the stem. The juvenile wood (rings 1-3) had small slopes and was dominantly inclined to the left throughout the stem. As ring number increased, the magnitude increased to maximum at rings 9-15, then gradually decreased throughout the stem. The only exception was at the base of the tree where slope increased steadily with ring number. Grain direction in the mature wood showed an increase in the proportion of right-hand grains as ring number increased and stem height decreased. No relationship was found between diameter growth rate and magnitude of slope. Spiral grain in the branches of these same trees showed a similar radial pattern, but no firm relationship between stem and branch grain could be discerned. Since 15% of the trees studied possessed excessive spiral grain, it was concluded that this defect substantially reduces the value of the lumber of P. oocarpa.

References

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Published

2007-06-27

Issue

Number 4 / October 1982

Section

Research Contributions

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