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24.3 Organization and Diversity of Roots
Rice, wheat, and corn are some of the most important food sources.
Perennials such as roses, irises, and potatoes use energy to make structures such as wood, bulbs, underground tubers, and leaf buds.
The modified organs help the plant survive.
Perennial plants, such as sunflowers and peas, produce enough structures to support flower and seed production.
The entire plant dies after seeds are dispersed.
Shoot apical meristem divides and leaves are made in the shoot system.
The timing of the genetic switches affects whether a plant is an annual or perennial.
Scientists have been able to induce annual plants to grow like perennial plants by blocking flower-inducing genes.
There are structural differences between the roots of monocots.
Most plants have a root system located underground.
The root system is equivalent in size and extent to the shoot system.
A corn plant has a smaller root system than an apple tree.
The root system of a plant anchor it in the soil, give it support, and absorb water and minerals.
The shape of a root allows it to penetrate the soil and allow water to be absorbed from all sides.
The capacity of a root is dependent on the number of branches and the root hairs near the tip.
The structures that absorb water and minerals are called root hairs.
hormones can be produced by roots and can be used in the storage of carbohydrates.
Storage roots include carrots and sweet potatoes.
The longitudinal section of a eudicot root shows where the cells are at various stages of development.
The root cap cells are ground off by rough soil particles as the root grows.
The root tip has three zones.
The eudicot root contains a cylinder of tissue.
Water and minerals must enter the xylem through the cell's cytoplasm because of the Casparian strip.
These can project as much as 8mm into the soil particles.
The cortex of the root is made up of large, thin-walled parenchyma cells.
The irregularly shaped cells are packed so that water and minerals can be absorbed in between the cells or travel through the middle of the root.
"skin" is the next layer of cells between the cortex and the inner vascular cylinder.
The water and ion that can move toward the vascular tissue can be regulated by the endodermal cells.
Water can move in between the cells of the cortex but can't go to the endodermis.
The pericycle, the first layer of cells within the cylinder, can continue to divide and be the starting point for branch or roots.
The xylem is shaped like a star because several arms of tissue are from a common center.
The phloem is found between the xylem's arms.
Eudicot roots have the same growth zones as monocot roots.
The organization of their tissues is different.
The ground tissue of a monocot root is surrounded by a ring of xylem and phloem bundles.
The roots of monocots have a number of body parts.
There is a ring surrounding a central pith in this overall cross section.
The placement of various tissues is shown in the enlargement.
There are two types of roots.
In eudicots, the first root grows straight down and is called a Monocots, which may have large numbers of similar diameter roots.
Many mature plants have tap root and fibrous root systems.
Some plants have roots that are able to adapt to their needs.
It is possible to improve anchorage to the ground.
Water, minerals, oxygen, and sunlight need to be absorbed by other root systems.
The roots of some plants, such as the sweet potato or carrot, are large enough to store a lot of food.
The corn prop roots support the plants in high wind.
Sweet potato plants have roots.
For support, prop roots are specialized.
Even though the tree lives in water, the pneumatophores allow it to get oxygen.
The aerial roots of orchids offer a number of benefits.
Roots normally get their oxygen from the air pockets in the soil, but oxygen becomes scarce when the plant grows exclusively in water.
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