These structures release cells that perform neutrophil-like functions by expelling extracellular DNA, called border cells. The movement of specialized organelles within the columella cells of these structures helps direct their growth according to the starch-statolith hypothesis. These structures can recover from damage by triggering the proliferation of stem cells located in quiescent centers. The lengthening of cells in the zone of elongation (-5[1])causes most of the growth (10[1])of these structures, (10[1]-5[1])which often display positive (-5[1])gravitropism. (-5[1])These structures form symbiotic relationships (10[1])with fungi called (10[1])mycorrhizae. Material in these structures is transported to the rest of the organism through the xylem. For 10 points, name these structures that plants use to take up nutrients and water. (10[1])■END■ (10[3])