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 (10[1])helps direct their (10[1])growth according to the starch-statolith hypothesis. (10[1])These structures can recover from damage by triggering the proliferation (-5[1])of stem cells (-5[1])located in quiescent centers. (10[2]-5[1])The lengthening of cells in the zone of elongation (10[1]-5[4])causes (10[1])most of the growth (10[2]-5[1])of these structures, (10[1]-5[5])which often (-5[2])display positive (10[1]-5[2])gravitropism. (10[4]-5[6])These (-5[1])structures form symbiotic (10[2])relationships (10[1])with fungi (10[2])called (10[7])mycorrhizae. (10[10])Material (10[1])in these structures (-5[1])is transported (10[1])to the rest of the organism (10[2])through (10[1])the (10[1])xylem. (10[1]0[1]-5[1])For 10 points, (-5[1])name these structures (10[2])that plants use to take (10[1])up nutrients (10[1])and water. (10[2])■END■ (10[18])