Plant Anatomy

• Plants have various types of organs and organ systems that perform specific functions.
• The shoot system of a plant consists of leaves, stems, flowers, and fruits.
• The root system of a plant consists of a single, thick root that branches into smaller roots.
• Roots are a part of the organ system that anchors the plant into the ground, absorbs water and minerals, and serves as a storage site for food.
• Root modifications are changes made to the root of a plant.
• The external root structure of a plant can be described as the part of the root that is above the soil.
• The internal root structure of a plant is the part of the root that is below the soil.
• Roots, stems, leaves, and flowers are all parts of plant structure.
• Jade plant cutting, showing adventitious roots growing from stem after being placed in water.
• Mung bean tap root (eudicot) and wheat bean fibrous root (monocot) from sprouts.
• Tap root systems have a main root that grows down, while fibrous root systems consist of many small roots.
• Primary root that originated from the root of the seedling and secondary (lateral) roots originate from the primary roots, and adventitious roots originate on stems or leaves, rather than from the base of the embryo.
• Adventitious roots can grow if plant cuttings are placed in water.
• There are two types of root systems: fibrous root system and tap root system.
• A tap root system has one main root that has branching into lateral roots, often seen in carrot-like plants.
• A fibrous root system has multiple big roots that branch and form a dense mass which does not have a visible primary root, often seen in grass-like plants.
• Plants that grow in dry areas often have deep root systems, whereas plants growing in areas with abundant water are likely to have shallower root systems.
• A tap root system has a main root that grows down vertically, and from which many smaller lateral roots arise.
• Eudicots have a tap root system, while monocots have a fibrous root system.
• Dandelions are a good example of a tap root system, as their tap roots usually break off when trying to pull these weeds, and they can regrow another shoot from the remaining root.
• Some plants have a combination of tap roots and fibrous roots.
• A fibrous root system is located closer to the soil surface, and forms a dense network of roots that also helps prevent soil erosion, often seen in lawn grasses, wheat, rice, and corn.
• A tap root system penetrates deep into the soil.
• Some roots with secondary growth may form a periderm, a protective layer, replacing the epidermis.
• The cork cambium arises from the pericycle and produces cork and phelloderm, forming the periderm.
• Cork cells are dead at maturity and produce a waxy substance called suberin, which functions to aid in water loss and makes the root more resistant to bacterial and fungal infections.
• The vascular cambium produces secondary xylem internally and secondary phloem externally.
• The cork cambium produces parenchyma tissues called phelloderm to the inside of the root and the cork on the outside of the root.
• The three layers of the periderm are phelloderm, cork cambium, and cork cells.
• The process of secondary growth in roots begins when the vascular cambium arises from the pericycle and embryonic tissue called the procambium.
• The formation of a cork cambium which originates from the pericycle is responsible for the formation of the periderm.
• Both cortex and pith include cells that store photosynthetic products.
• A layer of cells known as the endodermis borders the stele and is considered the innermost layer of the cortex.
• The zone of cell maturation is where the root cells begin to differentiate into special cell types.
• Root growth begins with seed germination, when the plant embryo emerges from the seed, the radicle of the embryo begins to grow downward and forms the root system.
• The root cap is a structure exclusive to roots and is continuously replaced because it gets damaged easily as the root pushes through soil.
• All three zones are in the first centimeter or so of the root tip.
• If you were to cut a cross section of the leaf, you could see other features that are not as obvious in the longitudinal section, including the cortex and the pith.
• The inner portion of the root contains the vascular tissue (xylem and phloem), this area is called the stele.
• The cortex is between the epidermis and the vascular tissue, whereas the pith lies between the vascular tissue and the center of the root.