Weed – Meaning, Types, Examples,

Weed is any plant that is not cultivated and is growing where it is not wanted. Such a plant is therefore a nuisance to the farmer. Examples: commelina, goat weed, or the common water leaf(Talinum triangular) growing in a cassava field.

Types of Weeds According to Lifecycle

1. Annual weed: They grow and complete their life cycle in one year
2. Perennial Weeds: They grow for more than one year.

Types of weeds according to the shape of their leaves

1. Broad-leaved Weeds: These are weed plants with broad leaves. They are dicotyledonous plants
2. Grasses and sedges: These plants have long, thin leaves and are monocotyledonous plants.

Examples of weeds

Some common weeds found in Nigeria are:

Common name                                                          Botanical name

1. Goat weed                                                            Argeratumconyzoides
2. Guinea grass                                                       Panicummaximum
3. Pig weed                                                              Amaranthusspinosus
4. Bahama grass                                                     Cynodondactylon
5. Elephant grass                                                   Pennisetumpurpureum
6. Carpet grass                                                       Axonopuscompresus
7. Tridax                                                                  Tridaxprocumbens
8. Spear grass                                                         Heteropogoncontortus
9. Sida weed                                                           Sidaacuta
10. Water leaf                                                           Talinumtriangulare

Characteristics of Weeds

They are:

1. Weeds grow very fast and cover the land area very quickly.
2. Many weeds produce fruits and seeds which are easily carried and spread all over the place by humans, animals, wind and water.
3. Many weeds are persistent, which means that they remain in the ground throughout the year and continue to grow as long as the weather conditions in the area permit and especially when cultivated crops are grown on the land.
4. They compete with crops for nutrients, space, water and sunlight.
5. They are resistant to harsh climatic conditions.

Advantages of weed

1. They serve as a source of food for man.
2. They serve as a source of feed to animals.
3. They increase the fertility of nutrient status of the soil directly or indirectly.
4. They help to control erosion.
5. They serve as a source of medicinal herbs for man.

Disadvantages of Weeds

1. Weeds compete with cultivated crops for the nutrients in the soil.
2. Weeds grow rapidly, hence they crowd and cover cultivated plants, thus preventing them from growing.
3. They make land cultivation difficult
4. Weeds which use crops as support can cause the strangling to death of such crops. e.g Parasitic weeds.
5. Transmission of insects, fungi and other organisms harmful to crops.
6. They result in a reduction in the value and quality of farm produce.
7. Wastage of money is controlled.
8. They increase farmers’ cost of production.
9. They lead to the loss of livestock when they consume poisonous weeds.

GENERAL EVALUATION/REVISION QUESTIONS

1. What is a weed?
2. Name three examples of weeds and their botanical names.
3. Mention three characteristics of weeds.
4. State five negative effects of weeds on crops and the economy.

THEORY

1. Define weed.
2. Mention the common names and botanical names of four weed you know.

See also

IMPORTANCE OF FARM ANIMALS

CHARACTERISTICS OF FARM ANIMALS

CHARACTERISTICS OF FARM ANIMALS

FARM ANIMALS

FORMS OF ENERGY