Fig. 123. Haematoxylon - Cross-section of wood.
P, Medullary ray, consisting of two vertical rows of cells, to which the black line from R should be extended. V, Pitted vessels. FL, Ligneous fibers. PL, Wood parenchyma.
This image is from Logwood in Sayre's Manual of Organic Materia Medica and Pharmacognosy, 1917.