Figure 2.

Giant redwood stem cross-sections 28 d after application of 0.1% Tween 20 (A), 100 mm MJ (B), ethylene (C), and 100 mm MS (D). Figures include similar region from each treatment with secondary phloem, cambium, and xylem for comparison. Bars = 200 μm. C, Cambial zone; F, fiber; PP, PP cell; R, ray parenchyma; S, sieve cells; X, xylem. A, Tween 20 control has normal anatomy of giant redwood, with regular secondary phloem pattern of a row of PP cells followed by sieve cells, fibers, and another row of sieve cells, and the absence of constitutive axial xylem ducts. B, MJ-induced PP cell swelling, phenolic accumulation, lignification of young fibers, and formation of axial xylem TDs. C, Ethylene treatment induced PP cell swelling and phenolic deposition and a row of TDs in the xylem. D, MS treatment did not induce anatomical changes.