Botany

The Plant Root

Aerial roots

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Aerial roots are a type of non parasitic, adventitious root that forms above ground and stays above ground. An aerial root will usually form on the stem or the base of a leaf. Some aerial roots, like those of the English Ivy, Virginia Creeper and poison ivy, help the vine cling to trees or other hard surfaces that they want to climb. These aerial roots end in a flat, suction cup shaped appendage which clings tightly to whatever surface it manages to adhere to.

Some aerial roots, like those that grow on orchids, actually have the ability to absorb water from the atmosphere. These roots develop a hard outer shell of dead cells which are called the velamen. These roots hang down into the damp, humid air and absorb whatever water they can from the air. The velamen is spongy, white and gives the root a silvery appearance. It will cover all of the root except the tip of the aerial root, which is green.

Botany

The Plant Root

Aerating roots

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Aerating roots

An aerating root is a root which arises above the water line on trees which grow in water like cypress and mangrove trees. Roots on these trees typically form protuberances which grow upwards and extend several inches above the waterline. In some tree species there are specialized cells which allow the exchange of oxygen between the atmosphere and the root.

Aerating roots are also referred to as knee root or knee or pneumatophores. In cypress trees there is no known function for the knee, as it does not seem to aid in gathering oxygen from the air. The aerating roots of the mangrove help to stabilize soil and provide habitat for wildlife in the areas that the tree grows in. The extensive root system of the mangrove also help to provide a barrier against the heavy winds of cyclones. In many countries in southeast Asia mangrove trees are grown along the coast for this purpose.

Most plants with aerating roots are found in swampy or wetland locations. Trees which develop aerating roots include:

Glyptostrobus
Bald Cypress
Pond Cypress
Ahuehuete
Metasequoia

Botany

Anatomy of the Root

Anatomy of the Root

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Most plant roots are composed of five main areas. These parts of the roots are the root tip, eperdermis, cortex, xylem and phloem.

The root cap is located at the very tip of the root. It is a thimble shaped structure which serves to protect the root tip, or apical meristem, which is composed of almost continuously growing cells.

The eperdermis is the skin of the root, composing its outmost surface. It is a single cell thick in most plants and it serves two functions, to protect the tissues within the root and to allow minerals and water to pass through. Microscopic root hairs grow outward from some of the cells of the eperdermis, greatly expanding the surface area of the root and increasing the amount of minerals and roots which may be taken in.

The next layer of the anatomy of a root is the cortex. The cortex is made up of parenchyma cells and the endodermis. Parenchyma cells mostly serve as storage structures and these are where excess food produced in the plant’s leaves are stored for future use. The endodermis is the innermost layer of the cortex. A waxy substance called the Casparian strip surrounds each cell, forcing minerals to pass through the cells of the endodermis by a process called osmosis, and not around them. This limits the amount of minerals and water passing into the cortex.

The vascular cylinder is the innermost layer of the plant root. It is composed of two structures, the xylem and the phloem. Both layers are composed of tube shaped cells and both have similar functions, the transportation of materials from one area of the plant to another. The xylem is composed of dead, tubular cells called veins, whose purpose is to transport minerals and waters to the stem and then on to the leaves, sort of like a pipe system within the plant root. The cells of the phloem are living cells, also tubular in shape and referred to as sieve tubes. The phloem also acts like a pipeline system, moving food manufactured in the leaves to either be used or stored in the cortex for future use.

The way the system functions is simple in concept. The root hairs take in water and minerals and pass it into the cortex. Pressure builds up, forcing them through the endodermis and into the phloem and from there up into the stem and outward to the leaves.

Botany

The Plant Root

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Of the three major organs of a plant the root is the most inconspicuous due to its existence underground. The root is the first organ to appear when the seed germinates and is known at the germination stage as the radicle. It’s first function is to anchor the developing seedling in the soil and take in water and nutrients from the soil. These functions, with the addition of becoming a food storage area for the plant, remain the primary functions of the root for the lifetime of the plant.

Depending upon the type of plant the radicle will develop into one of two major root systems, the tap root system or the fibrous system. Monocots like grasses tend to develop fibrous root systems. Dicots like carrot and most trees have what is called the tap root system. The fibrous root system of grasses, since they are the object of grazing by plant eating animals, serve to resist being pulled from the ground. Taproot systems for the larger plants help anchor the taller plants like trees, in the soil.

The root has developed various specialized tissues to aid it in its functions. These tissues are root hair, epidermis, epiblem, cortex, endodermis, pericycle and the vascular tissue. Generally the root hairs, using a process called osmosis, absorb water, nutrients and minerals from the soil. The root hairs transfer these materials to the vascular area which transports them to the rest of the plant for use. Legumes like peas and beans grow specialized structures called nodules which, in association with certain specialized bacteria, manufacture nitrogen for the plants use.

Roots grow from the tip using a group of specialized cells called the root cap to protect the root itself during growth. The roots will grow in any direction in the soil which satisfied their needs for moisture, nutrients and minerals.

Many plants have developed a specialized stem or bud structure which is often mistaken for roots. Gladioli have a specialized stem called a corm which grows underground and the root system emanates outward from the bottom of the corm. Potatoes have enlarged buds called tubers which grow underground and are often mistaken for roots.

Many roots like carrots, beets, horseradish and sweet potatoes are important food sources for humans and have enormous commercial value.

Common Name:
Red clover, Peavine clover, Cowgrass
Botanical Name:
Trifolium pratense
Family:
Fabaceae
Light:
Full sun
Soil:
Rich, moist.

Hardiness Zone:
USDA Zone 3 – 6
Propagation:
Seed
Flower Time – Southern Indiana:
May
Plant Height:
Six to twenty four inches
Flower Color:
Red
Type:
Perennial

Red clover

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The red flowers is a dense, rounded cluster of small flowers about one inch in diameter. Three oval shaped leaflets at the base of the flower cluster. The leaves are composed of three oval leaflets, each with a v shaped pattern near the middle of each leaflet. Clover is a valuable agricultural crop, prized for its food value for livestock and the ablility of the plant to fix nitrogen in the soil via nodules on the roots. It also has various medicinal uses and may be used to make a tea. It has become naturalized throughout the Midwest and other areas.

Red clover is an European plant which was introduced to America to be used as a forage plant for livestock. It is used in pastures and for hay.

Genus name from the Latin words Tri, meaning three and folium, meaning leaf. It refers to the three leaflets which make up the leaves.