Fig. 8.1-2. Transverse section of vascular bundle in a leaf of a grass (Botelua). Grasses are monocots, so this phloem shows the regular, easy-to-recognize organization typical of monocots (similar to Fig. 8.1-1). All the large, white cells are sieve tube members, all the small cells with dots (nuclei) are companion cells. Notice that the phloem is separated from the xylem by a barrier of fibers. Having a sheath of fibers is common for monocots, but this barrier between the two vascular tissues is a little unusual.