Page 24 – Vascular bundles in stem cortex
Fig. 21 . Vascular bundles in stem cortex. Transverse section of the stem of a 6-months-old plant to show the type of vascular bundle near the boundary between the cortex and stele. The bundle in A consists of phloem cells (sieve tubes and companion cells) surrounded by presclerenchyma cells which will form a fiber sheath, and the bundle sheath. The bundle in B consists of phloem separated by parenchyma from the xylem (consisting of a single trachea) and the whole surrounded by presclerenchyma cells, and the bundle sheath. bpc, parenchyma cell in bundle, separating phloem from xylem; bsc, bundle sheath cell (filled with tannin); cc, companion cell; cpc, cortical parenchyma cell; psc, presclerenchyma cell; sit, sieve tube; tr, trachea. X400.