Tissues and Cell Types
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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.
cells with thickened corners of their primary cell walls are
located just inside of the epidermis in this Helianthus
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.
stem xs. x40. Note the ring of vascular bundles in this
typical dicot stem.
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.
with scalariform pits. Lycopodium cone
with spiral pits. Lycopodium cone ls.
pores in the end walls of sieve tube elements. The sieve
pores appear as black dots. Moonseed vine xs. x1000.
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.
vine vascular bundle. The large diameter cells are vessels
within the xylem.
bordered pits in a tracheid. Pinus
macerated wood. x400.
pits in a tracheid. Pinus macerated wood.
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.
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.
vessel element with perforated end walls. Quercus
macerated wood. x100.
part of a FIBER. Note the relatively thick cell wall and the
presence of only a few pits. Quercus macerated
end of a FIBER. Note the tiny cell lumen in the center
surrounded by thick cell walls. Quercus macerated
vessel elements. Tilia macerated wood.
FIBER pointed end. Tilia macerated wood.
stack of vessel elements forming a vessel in wood. Tilia
wood rs. x100.
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.
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
(ring) pits in a vessel element. Zea mays
stem ls. x400.
and scalariform pits in a vessel element. Zea mays
stem ls. x400.
bordered pits. Pinus wood rs. x1000.
Plant Biology index
OSU Lima Biology