Plant Tissues and Cell types
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.
