A) Monocot root (Maize)
A transverse section of Maize root shows following structures:
1) Epiblema:
The outermost layer of the root is called as Epiblema or Rhizodermis. It is uniseriate and composed of compact tubular cells having no intercellular space and stomata. The tubular unicellular root hairs are present on this layer.
2) Cortex:
Immediately after epiblema there is a cortex region, it consists of parenchymatous cells. The starch grains are abundantly present in this region. The sclerenchyma cells are commonly found in the cortex of monocotyledons.
3) Endodermis :
The innermost layer of cortex is called as endodermis. It is composed of barrel shaped compact cells having no intercellular spaces among them. The endodermal cells possess casparian strips on their anticlinal wall.
4) Pericycle:
It is usually uniseriate and composed of thin walled parenchymatous cells. In monocotyledons, the pericycle may be interrupted by differntiation of xylem and phloem elements next to the endodermis.
5) Vascular tissue:
The vascular tissue consists of alternating strands of xylem and phloem. This is called as radical vascular bundle. The phloem occurs in the form of strnads near periphery of vascular cylinder, below the pericycle. The xylem forms discrete strands, alternating with phloem strands. The centre is occupied by large pith which may be parenchymatous or sclerenchymatous. Bundles are numerous and referred as polyarch.
 |
| Anatomy of Monocot root |
B) Monocot stem (Maize)
A transverse section of Maize stem shows following structures-
1) Epidermis:
The epidermis consists of single layer of compact cells having no intercellular spaces among them.
2) Hypodermis:
Below the epidermis usually two or three layers of sclerenchyma cells are present, called as hypidermis. It gives mechanical strength to the stem.
3) Ground tissue system:
It consists of thin walled parenchyma cells having well defined intercellular spaces among them. This tissue extends from below the sclerenchyma to the centre. It is not differentiated into cortex, endodermis, pericycle and pith.
4) Vascular system:
It is composed of many collateral and closed vascular bundles scattered in the ground tissue. The number of vascular bundle is more towards periphery than in the centre. Comparatively the peripheral bundles are smaller in size than that of Central bundles. Each bundle is more or less surrounded by sheath which is more conspicuous towards upper and lower sides. Usually xylem is Y-shaped and consists of pitted and bigger vessels of metaxylem and smaller vessels of protoxylem. The pith is not marked out in monocot stem.
 |
| Anatomy of Monocot stem |
C) Monocot leaf (Maize)
A transverse section of Maize leaf shows following structures:
1) Epidermis:
The epidermis is found on both upper and lower surfaces of the leaf. The epidermal layers are uniseriate and composed of more or less oval cells. The outer wall of the epidermal cell is cuticularised. The upper epidermis is easily identified by presence of xylem and bulifoem cells towards it. Stomata are present on both sides. Bulliform cells are in groups of 3 to 5 which reduce the rate of transpiration during draught. Stomata consist of two dumbbell shaped cells forming a small pore.
2) Mesophyll:
As the leaf is isobilateral, the mesophyll is not differntiated into palisade and spongy tissue. It is composed of compactly arranged thin walled, isodiametric chlorophyllous cells having well developed intercellular spaces among them.
3) Vascular bundles:
The vascular bundles are collateral and closed as found in monocotyledonous stem. Most of the bundles are small in size but fairly large bundles also occur at regular intervals. The xylem is found towards upper side and phloem towards lower side in the bundles. Usually each bundle remains surrounded by bundle sheath consisting parenchyma cells. The cells of bundle sheath generally contain starch grains in them.
