Figure 10.7Transverse sections of stems of Arceuthobium globosum illustrating variant (anomalous) secondary growth. A: whole stem, x3. B: individual block of vascular tissue, note that vascular cambium nearly encircles block, x40. C: vascular tissue showing vascular cambium (c) along flank of block (see upper left corner) and groups of protoxylem elements (px), x100. D: centrifugal direction of xylem differentiation at unlabeled arrows, note protoxylem at left of figure, x100.
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