CLASSES AND USES OF CROPS (CONTINUED) E-NOTE

WEEK: TEN

SUBJECT: AGRIC SCIENCE

CLASS: GRADE 7

TOPIC: CLASSES AND USES OF CROPS (CONTINUED)

CLASSIFICATION OF CROPS BASED ON MORPHOLOGY AND EXTERNAL FEATURES OF PLANTS

Plant possesses different characteristics while they are growing in the field or farm. These differences are seen in their root, stem, leaf, flowers and fruit characteristics/features. These characteristics have been used to classify plants into cereals, legumes, tubers, roots and fibres.

 i. Cereal Crops: Cereals are starchy and grain crops that are herbaceous. They are monocots. They produce long slender sword like leaves and form branches only at the base called tillers except maize and sorghum. This type of branching is called tuft growth. They are called energy giving food crops.

ii. Legume Crops: Legumes are herbaceous dicot plants. They have the tap-root system. Legumes have ways of fixing atmospheric nitrogen into the soil. This is because their roots bear nodules and bacteria such as rhizobium that are capable of fixing atmospheric nitrogen into the soil. They are rich in proteins which help to build the body and repair worn-out tissues. Examples cowpea, groundnut, soybean, pea, mung bean, lima bean, pigeon pea, bambara groundnut, etc.

iii. Root Crops: Roots crops are grown for their enlarged roots. The roots are enlarged due to their modification to store starch. They are starchy crops. Roots cannot be used as planting materials. Examples include cassava, carrot, beetroot, etc.

iv. Tuber Crops: Some crops have underground stems which are modified to store starch. Such crops are called tubers or tuber crops. They are starchy crops. They can be used as propagating or planting materials. Examples include yam, cocoyam, sweet potato, irish potato, etc.

v. Fibre Crop: They are crops that yield much fibre. Fibre crops are mostly herbaceous, and they are of three types viz:

 fruit fibres e.g cotton.

stem fibres e.g kenaf, jute.

leaf fibres e.g. sisal hemp.

Fibres are used in the production of ropes, fishing lines, sacks, etc.

CLASSIFICATION OF CROPS BASED ON USAGE/USES

i. Plants as Sources of Food: Many crops are grown for food. Some also serve as feed stuffs to animals. Plants that are commonly used as food include: rice, beans, yam, cassava, sweat potato, vegetables, etc.

ii. Crop plants serving as drugs: Some crops have healing properties and have been utilized for curative and preventive measures in treating and managing ailments. Examples include: Neem plant used in treating malaria, Bryophyllum used in treating wounds and swellings, mint basil used as antibiotics; pawpaw seeds which serve as worm expellers, cocoa plant used to manufacture analgesics; quinine-based anti malarial drugs, etc.

iii. Crops which provide timber coal and wood: Some benefits can be derived from crops, in terms of coal, wood and timber. The stems and branches of crops when dried can serve as source of fuel wood for cooking, baking and the powering of some engines. Big trees like iroko, mahogany, teak, gmelina, cotton tree, etc provide excellent timber which can be used in building houses (roofing), construction of bridges, doors, tables, cup boards, chairs/seats, boats/canoes, etc.

iv. Crops which provide sources of raw materials for industries: Many crop products serve as raw materials for industries. Cocoa seeds are utilized in beverage industries, latex from rubber is used in the manufacture of rubber tyres and tubes and even other rubber materials. Some plants provide raw materials for the production of paper, example gmelina tree and teak. Tea leaves are used for the production of tea bags. Coffee berries are used to produce coffee drinks. Oil crops such as oil palms and groundnut are used to produce various kinds of vegetable oils. Cotton plant produces cotton flint used in textile industries. Fruits such as pineapples, oranges, grapes, etc, are utilized by food, beverage and canning industries. Sugar factories use sugarcane and date palm as raw materials to produce fuel, table sugar, etc.

v. Crop plants which provide employment opportunities and income: Crop farming provides people with employment. Plantation farming provide jobs for people. People can become entrepreneurs by setting up their own crop farm enterprises (agri-preneurship). Every stage of crop production requires a lot of labour and manpower resources. People can earn their living through working in crop farms.

vi. Crops can be used for decorative purposes: Ornamental plants are used to beautify our environment. There are plants that produce attractive flowers that are used to beautify our surroundings, houses, lawns, parks, school premises, etc. Such flowers include: ixora, acalypha (red, cream, green, variegated), yellow bush, yellow ficus, Chinese rose, bourganvillea, rose flower, etc. Some flowers produce fragrance or scent which keeps the environment conducive. Example is queen of the night that perfumes the environment from 6.00pm to 6.am when it starts flowering. Flowers can be harvested and put in flower vases for decorating tables, rooms and halls. Examples include bourganvillea, pride of Barbados, hibiscus flower, alamanda, rose flower, cockscomb, harmattan lily, cana lily, flame of the forest (flamboyant tree), etc.

vii. Crops which produce export earning or foreign exchange: Nigeria used to export palm produce, groundnut, rubber, cocoa and coffee. The export of these crops was the driving force of the country’s economy before the crude oil boom of 1970’s.

ASSIGNMRNT

1. Classify crops based on morphology and external features of plants;

2. Classify crops based on usage/uses.