The Monocot Stem

Monocots are mostly annuals, meaning they live for only a single season. They are most readily recognized by their leaves; although there are exceptions, most monocot leaves exhibit parallel venation. A cross section of a monocot stem (figure 32-13) shows vascular bundles scattered in parenchyma. There may be a layer of sclerenchyma beneath the epidermis.

Epidermis

Vascular Bundles Monocot Stems

Ground Tissue

Vascular Bundle

Ground Tissue

Epidermis

Vascular Bundle

Figure 32-13 Cross section of a monocot stem.

# Notes £ Although this arrangement of vascular bundles represents the simplest organization of stem structures, it is believed to have evolved comparatively recently Examination of the xylem portion of the vascular bundle reveals two (or perhaps three) large vessels surrounded by small, thick-walled tracheids, see figure 32-14. In addition to the vessels, there is commonly another open space sometimes mistaken for a vessel but lacking a cell wall. This space is produced by a fracture; it is not a cell and is not involved in conduction. The phloem portion of the bundle shows sieve-tube elements with companion cells beside them. The entire bundle is surrounded by a bundle sheath of sclerenchyma. Outside the sheath is the parenchyma, consisting of large, thin-walled cells.

Phloem Vessel
Figure 32-14 Much enlarged portion of a monocot vascular bundle, (a) Sieve cell, (b) Xylem vessel, (c) Tracheid. (d) Parenchyma, (e) Fractured open space.

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  • lolita
    Why are monocot vascular bundles scattered?
    8 years ago
  • melissa
    Is green algae monocot or dicot?
    7 years ago
  • Debra
    What are the features of a phloem vessel?
    7 years ago
  • fnan
    Is green algae monocotyledon?
    3 years ago
  • ilmari
    What is the effect of vascular bundle for scattered in monocot stem?
    3 years ago

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