Characteristics of Monocotyledons
- The embryo of monocot plants only contains one cotyledon.
- Typically, monocots have a fibrous root structure.
- Monocot plants have leaves with parallel venation i.e., the veins are parallel to each other.
- There is no secondary growth in the monocot plant.
- Monocot stem has a vascular bundle that is distributed everywhere.
- There is no vascular cambium.
- Monocot plant have a lot of xylem and phloem groups and vascular bundles.
- The pith is prominent in the root.
- Three or more of the flowery whorls can be found in monocot plant.
- Monocot leaf has parallel venation.
Characteristics of dicotyledons
- The embryo of dicot plants has two cotyledons.
- Dicots often have a major tap root system.
- Dicot plants have leaves with reticulate venation, or networks or reticula instead of veins.
- The stem and root of the dicot plant exhibit secondary growth, which expands the plant’s circumference.
- The vascular cambium, from which the secondary xylem and phloem later developed, is present.
- In the dicot root, there is no pith.
- Dicot stem has a small layer of cuticle covering it, and it could have trichomes and a few stomata.
Difference between dicot and monocot stem
| Dicot stem | Monocot stem |
| Epidermis with multicellular hairs and stomata here and there guarded with kidney-shaped guard cells. | Outer surface of epidermis is cutinized: has stomata with dumb bell-shaped guard cell. |
| Collenchymatous hypodermis. | Sclerenchyma hypodermis. |
| Concentric arrangement of internal tissues. | Concentric arrangement is absent. |
| Ground tissue is differentiated into hypodermis, general cortex, endodermis, pericycle, pith etc. | Ground tissue is not differentiated. |
| Stem almost always solids. | Stem usually is not differentiated. |
| Vascular bundles arranged in ring around pith. | Vascular bundles are scattered throughout the ground tissue. |
| Dictyostele or eustele | Atactoced which is the most advanced type among the steles. |
| Pericycle made up alternating zone of parenchyma and sclerenchyma. | Pericycle mostly absent. |
| Vascular bundle 1. Few and similar size. 2. Conjoint, collateral and open. 3. Bundle sheath absent. 4. Wedge shaped in outline. 5. Phloem parenchyma present. 6. Protoxylem cavity is absent. 7. Vessels are usually arranged in rows or chains i.e., in linear fashion. | Vascular bundle 1. Numerous and smaller at the periphery and larger towards the central axis. 2. Conjoint, collateral and closed. 3. Enclosed within sclerenchymatous bundle sheath. 4. Oval or rounded in outline. 5. Phloem parenchyma absent. 6. Protoxylem cavity is present (expect asparagus). 7. Vessels are arranged in Y- shaped manner. |
| Medullary rays present. | Medullary rays are absent |
| Secondary growth is present. | Secondary growth is absent. |
Difference between dicot root and monocot root
| Dicot root | Monocot root |
| Cortex comparatively narrow. | Cortex very wide. |
| The epiblema, cortex and even endodermis are peeled off and replaced by cork. | Corks not formed. Only epiblema is peeled off. Cortex and endodermis persist. |
| Endodermis is less thickened and casparian stripes are more prominents. | Casparian stripes are visible only in young roots. Endodermal cells later become highly thickened. |
| Passage cells are generally absent. | Passage cells generally occur in endodermis opposite to proxylem. |
| Pericycle produces lateral roots. Cork, cambium, and vascular cambium. | Peri cycle produces lateral roots only. |
| Xylem and phloem bundles are diarch to hexarch (i.e., 2-6) | Xylem and phloem bundles are polyarchies i.e. >8. |
| Conjunctive tissue is parenchymatous. | Conjunctive tissues may be parenchymatous or sclerenchymatous. |
| Conjunctive parenchyma forms the cambium. | Does not form the cambium. |
| Pith small or absent. | Pith is well developed. |
| Protoxylem and metaxylem are arranged in linear fashion. | May be linear or V- shaped. |
| Secondary growth present. | Secondary growth is absent. |
Difference between dicot leaf and monocot leaf
| Dicot leaf | Monocot leaf |
| Cuticle thicker in upper epidermis than in lower epidermis. | Thickness of cuticle same in both epidermis. |
| Bulliform or motor cells absent. | Bulliform or motor cells are present. |
| Number of stomata greater in lower surface than upper. | Number of stomata equal in both surfaces. |
| Stomata guarded by kidney-shaped guard cell. | Stomata guarded by dumb- shaped guard cells. |
| Mesophyll divided into upper tightly packed palisading parenchyma and lower loosely arranged spongy parenchymatous. | Mesophyll normally not differentiated into spongy and palisade parenchyma. |
| Bundle sheath extension present in larger veins is parenchymatous. | Bundle sheath extension present is sclerenchymatous. |
| Bundle sheath cells are colorless. | Bundle sheaths are green and help in c4 cycle. This type is known as kranz anatomy. |
| Lysigenous cavity in xylem absent. | Lysigenous cavity in xylem usually present. |
