Cover.
Cover illustration: Cottongrass (Eriophorum vaginatum) is a perennial sedge that dies back to a small corm (left panel) as winter approaches. The following spring, flowering stems, adventitious roots, and new leaves all arise from this corm. The vascular system of the corm has two unusual features: (1) a ring of xylem and phloem encircling the vascular bundles that promotes the redistribution of nutrients among the leaves, roots, and storage tissues of the corm; and (2) groups of vascular sclerenchyma that provide a terminus for each of the vascular bundles and adventitious roots. Both the vascular ring and the vascular sclerenchyma participate actively in xylem (Safranine O dye: upper right panel) and phloem (fluorescein dye: lower right panel) transport. These unusual structures enable E. vaginatum to compete successfully in the nutrient-poor soils of the Arctic tundra (background). (See Cholewa and Griffith, pp. 731–741.)
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