Prunus. Fig. 1.—Transverse section of the stem bark of Prunus serotina.

Fig. 1.—Transverse section of the stem bark of Pru...

Fig. 1.—Transverse section of bark of Prunus serotina magnified 75 diameters. The specimen was from a stem only five or six years old.
a, cork, probably secondary periderm;
b, middle or green layer of bark;
c, clusters of stone cells in inner portion of middle bark;
d, compressed sieve tissue in the outer portion of bast layer;
e, a medullary ray;
f, mass of stone cells;
g, fissure between medullary ray and bast;
h, medullary ray;
i, cambium zone;
k, duct in mature wood.

This image is from Structure of our Cherry Barks in the September issue of the American Journal of Pharmacy, 1895.