Weeds: Characteristics, Uses And Classification of Weeds

A weed is a plant that grows in a place where it is not wanted e.g. a vegetable plant growing on a cassava plot is a weed.

Characteristics of Weeds

1. HIGH PRODUCTIVE CAPACITY: Weeds possess high productive capacity and are always the first to emerge and grow when necessary conditions are provided.  They have many seeds.  For example, a single grass head may produce thousands of seeds.
2. HIGH RESISTANCE CAPACITY: They are capable of withstanding adverse conditions because of their tough protective seed coats, e.g. seeds of some legume
3. ABILITY TO REGENERATE: Some weeds are capable of regenerating and, therefore, very difficult to eradicate. Commelina species, elephant grass and spear grass are examples of weeds that possess this characteristic
4. EARLY DISPERSED: Weed seeds possess various devices for dispersal.  These include spines, hooks, a parachute of hair, and wind with which they can easily be dispersed. tridax, goat weed and desmodium.
5. HIGH COMPETITIVE AND AGGRESSIVE GROWTH HABIT: Weeds possess a highly competitive growth habit and can easily smother crops. For example, spear grass, elephant grass can easily overrun a farm if not regularly checked.

Uses of Weeds

1. FOOD: Some weeds are used as food for man, e.g. African spinach (Amaranthus coudatus), cochurs olitorium e.t.c
2. ANIMAL FEEDS: Some weeds are used as food for feeding farm animals, e.g. guinea grass, sedge and elephant grass
3. MEDICINE: Most weeds are medicine.  A drug can be extracted from such weed,s e.g. lemon grass.
4. EROSION CONTROL: Weeds are used for control of tiny erosion, e.g. Bahama grass.
5. SOURCE OF ORNAMENTAL: Weeds are the major source of ornamental crops e.g. e.g. pride of Barbados, carno lily, rose, croton and hibiscus.

Classification of Weeds Based on Life Cycle

Weeds are grouped into three classes.  These include

1. Annual weed
2. Biennial weed 
3. Perennial Weed

ANNUAL WEED

These are weeds which complete their life cycle in one year.  They grow, reach maturity and die within a year.  Annual weeds include fridax plant, goat weed, spigelia and so on.

BIENNIAL WEEDS

These are weeds that complete their life cycle in two years.  The first year is used by the crops to grow and store food.  Reproduction and maturity take place in the second year.  Examples of biennial weeds are wild carrot, yellow rocket.

PERENNIAL WEEDS

These are weeds that take more than two years to complete their lifecycle or ripe for harvesting Perennial weeds include giant star grass, guinea grass, carpet grass, centxo and tropical kudzu.

COMMON WEEDS

COMMON NAME                             BOTANICAL NAME

1. Spear grass, Imperata Cylindrica
2. Guinea gras,s Panicum maximum
3. Elephant grass Pennisetum prupuren
4. Wild hemp Sida spp
5. Water leaf Talinum triangulare
6. Goat weed, Ageratum consoles
7. Stubborn grass Elaisina indica
8. W. D. Weed Tridax
9. Pig weed Boerhavia
10. Carpet grass, Axonopus compressus
11. Pigeon pea, a Cajanus caja
12. Sensitive plant Mimosu pudica
13. Witch weed, Striga senegalenesis

See also:

IMPORTANCE OF FARM ANIMALS

CHARACTERISTICS OF FARM ANIMALS

FORMS OF FARM ANIMALS

CLASSIFICATION OF CROPS ACCORDING TO THEIR USES

Common Diseases of Farm Animals