The phloem parenchyma cells resemble the sieve cells, but they are larger.
PLATE 91
Cross-Section of Rhizome of Spigelia marylandica, L.
1. Epidermis. 2. Cortical parenchyma. 3. Phloem. 4. Cambium. 5. Xylem. 6. Internal phloem. 7. Pith with starch.
PLATE 92
Cross-Section of Rhizome of Ruellia ciliosa, Pursh.
1. Epidermis. 2. Cystolith. 3. Stone cell. 4. Cortical parenchyma. 5. Bast fibres. 6. Pericycle. 7. Xylem. 8. Pith.
Cambium. The cambium cells are rectangular, and they are usually not clearly seen because the walls are partially collapsed.
Xylem. The xylem is composed of vessels, wood parenchyma, medullary rays, and pith parenchyma.
Vessels. The vessels are slightly angled in outline and few in number.