CLASSIFICATION OF WEEDS

Subject :Agricultural science

Topic :

CLASSIFICATION OF WEEDS

Class :

Basic 7 / JSS 1

Term :

Third Term

Week :

Instructional Materials :

• pictures of weeds
• samples of weeds

Reference Materials

• Scheme of Work
• Online Information
• Textbooks
• Workbooks
• 9 Year Basic Education Curriculum

Previous Knowledge :

The pupils have previous knowledge of

DEFINITION AND CHARACTERISTICS OF WEEDS

Behavioural Objectives :  At the end of the lesson, the pupils should be able to

• list classes of weeds
• mention at least four classes of weeds

Content :

CLASSIFICATION OF WEEDS

CONTENT

1. Classification of Weeds based on Habitat
2. Classification of Weeds based on Life Cycle
3. Classification of Weeds based on the Shape of the Leaves

Classification of Weeds based on Habitat

According to habitat, weeds are classified into the following three groups:

(a) Aquatic weeds: These are weeds that grow on water. Examples are water hyacinth, water lettuce, water lily etc.

(b) Terrestrial weeds: These are weeds that grow on land. Most weeds are terrestrial weeds. Examples are goat weeds, siam weeds, carpet grass, tridax, aspilia, elephant grass, water leaf, etc.

(c) Epiphytic/parasitic weeds: These are weeds that grow on other plants.

EVALUATION

1. Classify the following weeds in the table below; water lettuce, water leaf, tridax, dodder, water hyacinth, mistletoe.

Classification of Weeds based on Life Cycle

According to life cycle, weeds are classified into the following three groups:

1. Annual weeds: These are weeds that complete their life cycle within one year. Examples are goat weed, Tridax, Emilia weed, pig weed, Aspilia, milk weed, Amaranthus spp, water leaf, etc.
2. Biennial weeds: These are weeds that complete their life cycle in two years. Examples are morning glory, wild carrot, etc.
3. Perennial weeds: These are weeds that complete their life cycle in more than two years. Examples are elephant grass, broom weed, spear grass, bahama grass, Kudzu, siam weed, carpet grass etc.

Classification of Weeds based on the Shape of the Leaves

According to the shape of the leaves, weeds are classified into the following two groups:

1. Broad-leaved (dicotyledonous weeds): These are weeds that have short and broad leaves with net venation and taproot system. Examples are centro, stubborn weed, goat weed, water leaf, calapo, mucuna, etc.
2. Grasses and Sedges (monocotyledonous weed): These are weeds that have long and narrow leaves with parallel venation and fibrous root system e.g. gamba grass, carpet grass, maize, elephant grass, guinea grass, etc.

Presentation

The topic is presented step by step

Step 1:

The class teacher revises the previous topics

Step 2.

He introduces the new topic

Step 3:

The class teacher allows the pupils to give their own examples and he corrects them when the needs arise

:

EVALUATION

1. Mention two examples of the following: (i) Perennial weeds (ii) Annual weeds (iii) Biennial weeds
2. Explain the following with three examples each: (i) Monocotyledonous weeds (ii) Dicotyledonous weeds

Conclusion :

The class teacher wraps up or conclude the lesson by giving out short note to summarize the topic that he or she has just taught.

The class teacher also goes round to make sure that the notes are well copied or well written by the pupils.

He or she does the necessary corrections when and where  the needs arise.

Assignment :

Prepare for the next lesson by reading about

USES OF WEEDS; METHODS OF WEED CONTROL