. Identification of the economic woods of the United States, including a discussion of the structural and physical properties of wood . Pseudotsuga) are multiseriate. Thelatter, because of their shape as seen on tangential section, arecalled fusiform rays (Fig. 9). In woody Dicotyledons there is more variation in the rays.In some instances (e.g., JEsculus [Plate VI, Fig. 6], Salix, Populus)low uniseriate rays only are present. At the other extreme isQuercus (Plate III, Fig. 1), where the largest rays are from 25 to 26 ECONOMIC WOODS OF THE UNITED STATES 75 cells wide and several hundred high.
![. Identification of the economic woods of the United States, including a discussion of the structural and physical properties of wood . Pseudotsuga) are multiseriate. Thelatter, because of their shape as seen on tangential section, arecalled fusiform rays (Fig. 9). In woody Dicotyledons there is more variation in the rays.In some instances (e.g., JEsculus [Plate VI, Fig. 6], Salix, Populus)low uniseriate rays only are present. At the other extreme isQuercus (Plate III, Fig. 1), where the largest rays are from 25 to 26 ECONOMIC WOODS OF THE UNITED STATES 75 cells wide and several hundred high. Stock Photo](https://c8.alamy.com/comp/2CDCYD9/identification-of-the-economic-woods-of-the-united-states-including-a-discussion-of-the-structural-and-physical-properties-of-wood-pseudotsuga-are-multiseriate-thelatter-because-of-their-shape-as-seen-on-tangential-section-arecalled-fusiform-rays-fig-9-in-woody-dicotyledons-there-is-more-variation-in-the-raysin-some-instances-eg-jesculus-plate-vi-fig-6-salix-populuslow-uniseriate-rays-only-are-present-at-the-other-extreme-isquercus-plate-iii-fig-1-where-the-largest-rays-are-from-25-to-26-economic-woods-of-the-united-states-75-cells-wide-and-several-hundred-high-2CDCYD9.jpg)
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. Identification of the economic woods of the United States, including a discussion of the structural and physical properties of wood . Pseudotsuga) are multiseriate. Thelatter, because of their shape as seen on tangential section, arecalled fusiform rays (Fig. 9). In woody Dicotyledons there is more variation in the rays.In some instances (e.g., JEsculus [Plate VI, Fig. 6], Salix, Populus)low uniseriate rays only are present. At the other extreme isQuercus (Plate III, Fig. 1), where the largest rays are from 25 to 26 ECONOMIC WOODS OF THE UNITED STATES 75 cells wide and several hundred high. These large rays give riseto the handsome figure of quarter-sawed (i.e., radially cut) oaklumber. Besides the large rays in Quercus there are numerousintermediate ones, mostly uniseriate and 1-20 cells high (PlateIII, Fig. 1). In Platanus the rays are uniformly broad (10-15cells), while in Fagus only a portion of the rays are broad (15-25cells), the intermediate ones being uniseriate. In some of theevergreen oaks, Carpinus and species of Alnus (Plate V, Figs. 3, 4), the large rays appear to be composed of numerous small ones r.tr.. rjtr. Fig. 5.—Radial section of a ray of Pinus edulis (pinon pine), showing thesmooth upper and lower walls of the ray tracheids (r. ir.), and the presence in thelateral walls of the ray-parenchyma cells (r. p.) of small semi-bordered pits (s. b. p.), communicating with the wood tracheids (w. tr.) adjacent; s. p., simple pit; 6. p., bordered pit. Magnified about 250 diameters. separated by wood fibres. Such rays are termed aggregate orcompound rays; sometimes also false rays. Every ray, regardlessof its width at the middle, tapers to an edge so that the upperand lower margins are a single cell wide.* The comparative distinctness which rays on cross sectionpresent to the unaided eye is important in separating certainwoods which bear superficial resemblance. For instance, the * For this reason cross sections often do not afford a correct idea of raywidt