ClipArt ETC
First developmental stage of sieve tubes, companion cells, and phloem parenchyma. "A, a and b, two rows of procambial cells; in c and d, a has divided longitudinal and c is to become companion cells; d, a sieve tube, and b, phloem parenchyma." -Stevens, 1916

Plant Cell Development 1

First developmental stage of sieve tubes, companion cells, and phloem parenchyma. "A, a and b, two rows…

Second developmental stage of sieve tubes, companion cells, and phloem parenchyma. "B, c, companion cells, and d, a beginning sieve tube from c and d, respectively in A. The cross-walls in d are pitted; b, phloem parenchyma grown larger." -Stevens, 1916

Plant Cell Development 2

Second developmental stage of sieve tubes, companion cells, and phloem parenchyma. "B, c, companion…

Third developmental stage of sieve tubes, companion cells, and phloem parenchyma. "The pits in the cross-walls of the sieve tubes become perforations, and the nuclei gone from the cells composing the tube." -Stevens, 1916

Plant Cell Development 3

Third developmental stage of sieve tubes, companion cells, and phloem parenchyma. "The pits in the cross-walls…

"Diagram to show food from the leaves descending through the sieve tubes and being stored in the medullary ray cells and xylem parenchyma." -Stevens, 1916

Plant Food Storage

"Diagram to show food from the leaves descending through the sieve tubes and being stored in the medullary…

"Diagram indicating the succession of the conducting tissues of a vein from the base toward the apex. a, border parenchyma; b, companion cells; c, sieve tubes; d, undivided mother cells of companion cells and sieve tubes; e, tracheal elements." -Stevens, 1916

Plant Vein

"Diagram indicating the succession of the conducting tissues of a vein from the base toward the apex.…