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Figs. 15-20. Transections of pith. (15) D. plantaginea, X 75. (16) D. linearis, X 80. (17) D. latifolia, X 84. 
(18) D. Menziesii, X 78. (19) Ar^>roxiphium Caliginii, X 72. (20) A. sandwichense; packets of pith tracheids at 
right; groups of procambial cells below and left; X 90; inset shows bordered pits between two pith tracheids, 
X 870. 
