COURSE CODE: PAB 310

COURSE TITLTE: ECONOMIC AND MEDICINAL

CLASSIFICATION AND FOOD VALUE OF VEGETABLES

Vegetables are the main sources of nutrients such as vitamins, minerals that enrich and diversify human diets. Vegetable forms an integral part of agricultural systems worldwide, they are grown as food in subsistence and commercial farming.

Vegetable as defined by Radovich (2011) as any part consumed for food that is not a mature fruit or seed. These include petioles (e.g., celery, Apium gravelons), leaves (e.g., Lettuce, Lactuca sativa, Lagos-spinach Celosia argentea), immature fruits (e.g. cucumber, Cucumis sativus), roots (e.g., carrot Dacus carota) and specialized structures such as bulbs (e.g. onion Allium cepa) and tubers (e.g. potato, Solanum tuberosum). An exception or inclusion to this definition is the mature fruit (e.g. tomato Solanum lycopersicum), beans, melons Cucumis melo etc. which are fruits by every botanical definition both are usually “termed” vegetables because of similarities in biology and culture that they share with vegetal Cucubitaceae.

In addition to the vegetables plants in Kingdom Angiospermae mentioned above, some fungi (e.g. cremini mushroom Agaricus bisporus) in the Kingdom Tallophyta are also regarded as vegetables.

Vegetables can be classified in different groups, based on commonalties among groups:

1. Tissues and organs consumed 2. Ecological adaptation 3.

Other form of classification of vegetables is by the edible parts (which is common to layman) is termed “Supermarket Botany” (Graham et al., 2006).

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Classification of vegetables based on the “edible parts”

Generally based on the edible part, vegetables could be classify as

1. Leafy Vegetables

Leaves are known as the main photosynthetic organ, they contains highest percentage of photosynthetic products and are the most perishable of the vegetables. Dark green leaves contains high levels of minerals (e.g. Fe, Mg, Ca), enzymes (protein), and secondary metabolites (e.g. carotenes, xanthophylls and flavonoids), which are of importance to human nutrition. Leaves are known to contain higher amount of stomata on the abaxial surface combined with its high surface area, makes leafy vegetables more susceptible to postharvest water-loss than other vegetables. Therefore, it was recommended that cooling after harvest and storage under high humidity are important postharvest procedure (Kader, 2002).

Leafy vegetables that are generally cooked before consumption to soften texture and improve flavor are classified as “greens”, examples are Brassica spp (cabbage), Corchorus olitorious (jute or ewedu), Celosia argentea (Cockscomb), Gnetum africanum (Ukazi or Afang leaves), e.t.c. While those consumed raw are referred to as “salads” (e.g. most members of compositae, young leaves of Bassica spp., Lettuce, e.t.c.). Lastly, “potherb” is used to describe green used in small quantity for flavouring in cooking e.g. Ocimum spp. (Scent leaf), Piper guineensis (Uziza or false cubeb leaves), e.t.c.

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Pictures of some leafy vegetables

Celosia argentea (Cockscomb or Lagos spinach) Image source: https://www.ebay.com/itm/NEW-10-Seeds-yellow-Celosia-argentea-L-Cockscomb- Chinese-Wool-Flower-/123813477999

Brassica oleracea (cabbage) Image source: https://www.monaconatureencyclopedia.com/brassica-oleracea/

Piper guineensis (Uziza leaves)

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2. Root Vegetables

These includes true roots such as carrot, sweet potato and cassava as well as specialized structures such as tubers, bulbs, corms (e.g. taro), and hypocotyls (e.g. radish, Raphanus sativus). These are classified as root vegetables because of their full or partial subterranean habit, their proximity to true roots and their function as storage organ for starch and other compounds.

Tubers are modified stems, they are enlarged, fleshy underground stems that share some characteristics of true roots examples are white potato (Solanum tuberosum) and yams (Dioscorea spp.).

Raphanus sativus (Radish) Image source: https://www.google.com/imgres?imgurl=https

Solanum tuberosum (Irish potato or white potato)

Image source: https://www.naturepl.com/stock-photo-visuals-unlimited-nature- image01310684.html

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3. Stem vegetables

These comprises of the stem lettuce (Latica sativa), broccoli (Brassica oleracea), Asparagus (Asparagus officinalis), bamboo shoot, e.t.c.

Asparagus officinalis (Asparagus) Image source: https://www.ebay.com/itm/Asparagus-officinalis-EMERALD-/202742084758

Bambusa vulgaris (Bamboo shoot) Bamboo shoot dish (Stir-fried tofu with bamboo shoot)

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4. Fruit vegetables

They are mostly found in the Family Solanaceae, Cucurbitaceae and , and other familes. For example Abelmochus esculentus (okra), Phaseolus spp.(bean), Solanum lycopersicum (tomato), Solanum melogena (eggplant), Cucumis sativus (cucumber), e.t.c.

Abelmochus esculentus (okra or okro)

Solanum melogena var. insanum (eggplant)

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5. Flower vegetables

These are consumed raw or cooked. They are mostly inflorescence examples are broccoli and globe artichoke (Cynara scolymus).

Brassica oleracea (Broccoli) Image Source: http://myseedgarden.blogspot.com/2010/01/brocoli-waltham-39.html

Cynara scolymus (Globe artichoke) https://www.shutterstock.com/search/globe+artichoke

Aside the aforementioned criteria, vegetable can also be classified based on 1. Life cycle (annuals, biennial and perennials) (Pierce, 1987)  Annuals examples are Spinacia oleracea, Cucurbita spp., Brassica oleracea  Biennials examples are Beta vulgaris, Brassica oleracea Capitata group, Dacus carota

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 Perennials examples are Asparagus officinal , Capsicum spp., Ipomea batatas, Solanum sp

2. Temperature growth requirements (Pierce, 1997)  Hot (18–35◦C) Abelmochus esculentus, Citrullus lanatus, Capsicum chinense  Warm (12–35◦C) Cucumis sativus, Cucurbita spp., Zea mays, Capsicum annuum  Cool (heat tolerant) (7–30◦C) Colocasia escultenta, Allium spp., Cynara scolymus, Brassica rapa L. Chinensis group  Cool (7–25◦C) Brassica oleracea, Raphanus sativus, Latuca sativa, Solanum tuberosm

3. Based on Photoperiodicity  Short day Amaranthus spp., , Solanum tuberosum  Day neutral Solanum lycopersicum, Phaseolus spp., Cucurbita spp.  Long day Allium cepa Cepa group, Spinacia oleracea

References

Graham LE, Graham JM, Wilcox LW. 2006. Plant Biology, 2nd edition. Upper Saddle River, NJ: Pearson/Prentice-Hall. Krug H. 1997. Environmental influence of development growth and yield. In: Wein HC (editor), The Physiology of Vegetable Crops. New York: CAB International, pp. 101–206. Krug H. 1997. Environmental influence of development growth and yield. In: Wein HC (editor), The Physiology of Vegetable Crops. New York: CAB International, pp. 101–206. Peirce L. 1987. Vegetables: Characteristics, Production and Marketing. New York: John Wiley and Sons. Radovich T.J.K.2011. Biology and Classification of Vegetables In: Handbook of Vegetables and Vegetable Processing. Sinha N.K. (editor) Wiley-Blackwell.

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Assignment 1

In a tabular form, list five leafy, fruit and root vegetables each cultivated and consumed in your state of origin. State their botanical, local and common (or English) names.

For example

State: Osun Locality: Iwo

Leafy Vegetable Botanical name Local name Common name 1 Celosia argentea Soko yòkòtò Cockscomb or Lagos spinach

Fruit Vegetable Botanical name Local name Common name 1 Abelmoschus esculentus Ila Okro

Root Vegetable Botanical name Local name Common name 1 Manihot esculenta Gbaguda (or Cassava ègé)

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