Plant Tissues and Cell Types

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  • Coleus stem xs. x40. The pointer shows a vascular bundle. Numerous PARENCHYMA cells are in the center. A small thickness of secondary tissue consisting of straight rows of cells exists between and within the vascular bundles.
  • COLLENCHYMA cells with thickened corners of their primary cell walls are located just inside of the epidermis in this Helianthus stem. x400.
  • PARENCHYMA cells are located in the central pith and the cortex of this Helianthus stem. x100. Each vascular bundle has a dense layer of fibers, then green staining phloem, then red staining xylem with large vessels as you move from the outside toward the inside of the vascular bundle.
  • Helianthus stem xs. x40. Note the ring of vascular bundles in this typical dicot stem.
  • Sieve tube and sieve plate, ls.. Two sieve tube elements are separated by a porous sieve plate. The red substance is callose, a carbohydrate plants use to plug their sieve pores when phloem is injured. Cucumber stem x400.
  • TRACHEIDS with scalariform pits. Lycopodium cone ls. x1000.
  • TRACHEIDS with spiral pits. Lycopodium cone ls. x1000.
  • Sieve pores in the end walls of sieve tube elements. The sieve pores appear as black dots. Moonseed vine xs. x1000.
  • Phloem region within a vascular bundle. From right to left (from the outside toward the center of the stem) you can see red staining thick walled FIBERS, then SIEVE TUBE ELEMENTS some with sieve plates and their sieve pores, and then the vascular cambium. Moonseed vine xs. x400.
  • Moonseed vine vascular bundle. The large diameter cells are vessels within the xylem.
  • Circular bordered pits in a tracheid. Pinus macerated wood. x400.
  • Simple pits in a tracheid. Pinus macerated wood. x400.
  • Circular boardered pits seen from the side. The "boarder" is actually secondary cell that has separated from the primary cell wall. The dark structures are thick areas of primary cell wall inside the pit apeture, or hole, within the secondary cell wall. Pinus wood. rs. x1000.
  • Large diameter vessel element. The diameter is almost as great as the (short) length of the cell. Note the perforated ends and the pits on the lateral wall. Quercus macerated wood. x100.
  • Another vessel element with perforated end walls. Quercus macerated wood. x100.
  • Central part of a FIBER. Note the relatively thick cell wall and the presence of only a few pits. Quercus macerated wood. x400.
  • Pointed end of a FIBER. Note the tiny cell lumen in the center surrounded by thick cell walls. Quercus macerated wood. x400.
  • Tilia vessel elements. Tilia macerated wood. x100.
  • Another FIBER pointed end. Tilia macerated wood. x400.
  • A stack of vessel elements forming a vessel in wood. Tilia wood rs. x100.
  • A single Helianthus vascular bundle. x100. Note collenchyma cells near the outside of the stem and parenchyma cells near the center. The vascular bundle shows from the outside in fibers, phloem, vascular cambium, and xylem. The large red staining cells within the xylem are vessel elements.
  • Vessel in a corn stem. The vessel consists of several stacked vessel elements. To the right of the vessel are green staining phloem cells and red staining fibers, all of which form part of a vascular bundle seen here in longitudinal section. Zea mays stem ls. x100.
  • Annular (ring) pits in a vessel element. Zea mays stem ls. x400.
  • Simple and scalariform pits in a vessel element. Zea mays stem ls. x400.
  • Circular bordered pits. Pinus wood rs. x1000.

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