Horticulture and Botanical Classification of Horticultural Crops

Horticulture and Botanical Classification of

Horticultural Crops

India has a wide range of growing environments, ranging from dry conditions in subtropical plains and plateaus to humid tropical coastal regions, while hilly and high-altitude areas experience cool to severely cold conditions. These diverse eco-edaphic conditions support a rich diversity of plant wealth in the country. A large number of fruits, vegetables, spices, plantation crops and other economically important plants are cultivated under different growing conditions.

Considerable variation exists among plants in their growth habit, flowering and fruiting behaviour, nutritional quality, response to environment and other characteristics. Studying each plant separately can therefore become difficult and repetitive. To overcome these difficulties, plants are grouped according to their similarities and dissimilarities in various characteristics. Such grouping of plants into different categories is referred to as classification. The main objective of classification is to systematize the study and make the identification, comparison and study of plants easy and convenient.

Objective of classification

Classification of plants means grouping different plants having some characteristics in common. It is a relatively dynamic process and undergoes changes with the advancement of knowledge.

1. To get familiar with the different horticultural crops.
2. To identify and classify different horticultural crops.
3. To know their economic value and importance.
4. To determine their adaptability to the local environment.
5. To facilitate easy and quick cultural operations.
6. To facilitate breeding and the development of new varieties.
7. To facilitate propagation of crops.
8. To facilitate effective control of pests and diseases.
9. To help in cultivating crops suitable for different climatic conditions.

Nomenclature and Basic Taxonomic Classification

Early classification started with the Greek philosopher Theophrastus, who classified all plants into annuals, biennials, and perennials according to life spans, and into herbs, shrubs, and trees according to their growth habits.

Modern taxonomy for plant classification is based on Linnaeus (an 18^th-century^* Swedish physician, now considered “Father of taxonomy”) who revolutionized the fields of plant and animal classification.

Horticulture deals mostly with family, genus, species and cultivars. Scientific names of species are generally binomial. The genus and species are written in italics (or underlined when handwritten), whereas family and cultivar names are not italicized or underlined.

Classification of Horticultural Crops

Horticultural crops are broadly classified into the following groups:

1. Vegetable Crops
2. Fruit Crops
3. Floricultural
4. Plantation Crops
5. Medicinal Crops
6. Aromatic Crops
7. Spice Crops

Part 1. Vegetable Crops

Classification is the systematic method of grouping different plant species for identifying and cataloguing information about cultivated plants and crops.

According to Kees and Dais (1985–1996), about 392 vegetable crops are cultivated worldwide, belonging to around 70 families and 225 genera. Vegetable crops are diverse in their edible parts, including leaves, young shoots, fruits, roots, tubers, rhizomes, corms and stolons. Many vegetable crops also have more than one edible part. The importance of individual vegetable crops varies among countries according to their dietary patterns and food habits.

Botanical classification is largely based on morphological variability among plants, with reference to flower type, morphology and sexual compatibility. The basic and useful taxonomic groups are family, genus, species and cultivar. The binomial system of nomenclature was presented in Species Plantarum, published by Linnaeus in 1753^**, and became a foundation of modern botanical nomenclature.

The International Code of Botanical Nomenclature (ICBN), Atrect, (Netherland) now known as the International Code of Nomenclature for algae,fungi, and plants (ICN), is a set of rules and recommendations governing the scientific names of algae, fungi and plants. The name was changed from ICBN to ICN at the XVIII International Botanical Congress held in Melbourne in 2011.

The International Code of Nomenclature for Cultivated Plants (ICNCP), also known as the Cultivated Plant Code, provides rules and recommendations for the naming of cultivated plants (cultigens) whose origin or selection is primarily due to intentional human activity. It particularly deals with cultivated plant categories such as cultivars.

Vegetable crops can be classified in different ways based on their botanical relationships, temperature tolerance, soil and environmental requirements, edible parts, cultural practices, physiological characteristics and other important traits. The major classifications of vegetable crops are as follows:

A. Botanical, Climatic and Environmental Classification

1. Based on Botanical Relationship
2. Based on Climatic Zones
3. Based on Temperature Requirement (Thermoclassification)
4. Based on Growing Seasons
5. Based on Hardiness
6. Based on Tolerance to Soil Acidity
7. Based on Tolerance to Soil Salinity/Soil Salt Content
8. Based on Tolerance to Salt (NaCl Concentration)
9. Based on Soil Factor
10. Based on Water Relationship
11. Based on Water Requirement
12. Based on Rainfall and Irrigation Requirement
13. Based on Root Depth in Soil
14. Based on Lime Requirement

B. Edible, Chemical and Nutritional Classification

   15. Based on Edible Parts Used as Vegetable
   16. Based on Predominant Organic Acid Present
   17. Based on Vitamins and Nutritional Value
   18. Based on Plant Pigments
   19. Based on Toxic Substances Present in Vegetable Crops

   20. Based on Chemical Compounds Present in Vegetable Crops (Aroma, Pungency, Flavor     and Phytochemicals)

C. Seed, Propagation and Crop Establishment Classification

   21. Based on Seed Sowing and Planting Methods
   22. Based on Propagation Materials
   23. Based on Transplanting Requirement
   24. Based on Suitable Age for Transplanting
   25. Based on Forcing Requirement
   26. Based on Seed Rate
   27. Based on Nursery Bed Requirement
   28. Based on Isolation Distance
   29. Based on Optimum Soil Moisture Requirement

D. Physiological and Reproductive Classification

   30. Based on Photoperiodism
   31. Based on Photosynthetic Pathway
   32. Based on Sex Form
   33. Based on Pollination Mechanism
   34. Based on Mode of Pollination
   35. Based on Floral Biology and Reproductive Behaviour
   36. Based on Self-Incompatibility
   37. Based on Male Sterility

E. Seed and Genetic/Breeding Classification

   38. Based on Seed Storability
   39. Based on Seed Germination
   40. Based on Food Storage in Seeds
   41. Based on Morphological Markers
   42. Based on Combining Ability

F. Respiration and Post-harvest Classification

   43. Based on Respiration Rate of Produce
   44. Based on Respiratory Behaviour
   45. Based on Ethylene Production
   46. Based on Storage Life of Vegetable Produce
   47. Based on Storage Temperature

G. Morphological Classification

   48. Based on Fruit Type and Fruit Anatomy
   49. Based on Inflorescence Type
   50. Based on Tendril Type in Cucurbit Vegetables
   51. Based on Modification of Plant Parts

H. Cultural Classification of Vegetable Crops

   52. Based on Cultural Classification of Vegetable Crops

I. Vegetable Garden Classification

   53. Based on Type of Vegetable Garden

 

A. 1. Based on Botanical Relationship

Vegetable crops are broadly classified into Monocotyledons and Dicotyledons based on their botanical relationship.

A. Monocotyledons

S. No.	Family	Crop	Botanical Name	Chromosome Number (2n)	Origin
1	Amaryllidaceae (Alliaceae)	Onion	Allium cepa	16	Central Asia
		Garlic	Allium sativum	16	Central Asia
		Leek	Allium porrum	2n=4x=32 (tetraploid)	Central Asia
		Shallot	Allium cepa var. ascalonicum	16	Central/South-West Asia
		Chive	Allium schoenoprasum	16, 24, 32	Asia & Europe
		Welsh onion	Allium fistulosum	16	China
		Kurrat / Egyptian leek	Allium ampeloprasum var. kurrat	2n=4x=32 (tetraploid)	Southern Europe to Western Asia
2	Araceae	Elephant foot yam	Amorphophallus companulatus	28	India/Sri Lanka
		Colocasia / Taro	Colocasia esculenta spp. /Colocasia esculenta (L.) Schott	2n=2x=28*** (diploid), 2n=2x=42 (triploid)	Sri Lanka / Southeast Asia
		Tannia	Xanthosoma sagittifolium	26	South America
		Giant taro	Alocasia macrorrhizos	28	Rainforest of Borneo & Queensland
		Swamp taro	Cyrtosperma merkusii	26	Western Malaysia
3	Dioscoreaceae	Lesser yam	Dioscorea esculenta	2n=2x=40	Indo-Burma
		Greater yam	Dioscorea alata	2n=2x=40	Indo-Burma/Southeast Asia
		White yam	Dioscorea rotundata	2n=2x=40	Indo-Burma/West Africa
4	Poaceae (Gramineae)	Sweet corn	Zea mays var. rugosa	20	Mexico1/Central America/peru
5	Liliaceae	Asparagus	Asparagus officinalis	20	Mediterranean region
6	Cannaceae	Queensland Arrowroot	Canna indica	18****	South America
7	Cyperaceae	Chinese water chestnut	Eleocharis dulcis	—	Asia (China)

S. No.	Family	Crop	Botanical Name	Chromosome Number (2n)	Origin
1	Amaryllidaceae (Alliaceae)	Top onion	Allium cepa var. viviparum	16	Central Asia
		Multiplier onion	Allium cepa var. aggregatum	16	South-West Asia/Central Asia

B. Dicotyledons

S. No.	Family	Crop	Botanical Name	Chromosome Number (2n)	Origin
1	Aizoaceae15	New Zealand spinach	Tetragonia tetragonioides	32	New Zealand/Australia2
2	Amaranthaceae	Chhoti chaulai	Amaranthus blitum	32	India
		Badi chaulai	Amaranthus tricolor	32	India
3	Basellaceae	Indian spinach (Malabar night shade)	Basella alba (green), Basella rubra (red)	44, 483	India
4	Chenopodiaceae14	Spinach	Spinacia oleracea	12	Iran/Central Asia4
		French spinach	Atriplex hortensis	18	Europe & Asia
		Palak/beet leaf/spinach beet	Beta vulgaris var. bengalensis	18	Indo-China
		Beetroot	Beta vulgaris var. rubra	18	Mediterranean region
		Swiss chard5	Beta vulgaris var. cicla	18	Mediterranean region
5	Compositae (Asteraceae)	Lettuce	Lactuca sativa	18	Mediterranean region
		Chicory	Cichorium intybus	18	Europe/Mediterranean region
		Endive	Cichorium endivia	18	Mediterranean region
		Globe artichoke	Cynara scolymus	34	Mediterranean region
		Jerusalem artichoke	Helianthus tuberosus	2n=6x=102 (hexaploid)	North America/ USA
6	Convolvulaceae	Sweet potato	Ipomoea batatas	2n=6x=90 (hexaploid)	South America
7	Cruciferae (Brassicaceae)	Cabbage	Brassica oleracea var. capitata	18	Mediterranean region
		Cauliflower	Brassica oleracea var. botrytis	18	Mediterranean region
		Knol-khol	Brassica oleracea var. gongylodes	18	Mediterranean region
		Sprouting broccoli	Brassica oleracea var. italica	18	Mediterranean region
		Brussels sprout	Brassica oleracea var. gemmifera	18	Mediterranean region
		Kale	Brassica oleracea var. acephala	18	Mediterranean region
		Radish	Raphanus sativus	18	Europe
		Turnip	Brassica rapa	20	Asia
		Chinese cabbage	Brassica chinensis/Brassica rapa subsp. Pekinensis6	20	China
		Rutabaga (Swede)-Man made vegetable	Brassica napus var. napobrassica	38
		Leaf mustard	Brassica juncea var. cunefolia	36	Central Asia7
8	Cucurbitaceae	Cucumber	Cucumis sativus	14	India
		Musk melon	Cucumis melo	24	Tropical Africa
		Snap melon  (Phoot)	Cucumis melo var. momordica	24	Tropical Africa
		Long melon (Kakri)	Cucumis melo var. utilissimus	24	Tropical Africa
		Gherkin	Cucumis anguria	24	Tropical Africa
		Watermelon	Citrullus lanatus	22	Tropical Africa
		Tinda (Round melon)	Citrullus lanatus var. fistulosus	22	India
		Bottle gourd	Lagenaria siceraria	22	South Africa/India
		Bitter gourd	Momordica charantia	22	Indo-Burma
		Kakrol (Sweet gourd)	Momordica cochinchinensis	28
		Spine gourd (Kartoli)	Momordica dioica	28
		Teasle gourd	Momordica subangulata ssp. renigera	56	South/Southeast Asia
		Ridge gourd	Luffa acutangula	26	Asia/India
		Sponge gourd	Luffa aegyptiaca Milli (luffa cylindrica)8	26	Assam
		Pumpkin	Cucurbita moschata	40	Tropical America/ Mexico
		Summer squash	Cucurbita pepo	40	Mexico/Central America
		Winter squash	Cucurbita maxima	40	Bolivia to northern Argentina9/South America
		Buffalo gourd	Cucurbita ficifolia	40	North America
		Cooking melon	Cucumis melo subsp. Agrestis var. conomon	24	Africa & Asia
		Pointed gourd	Trichosanthes dioica	22	India
		Chow-chow / Chayote	Sechium edule	28	Central America/ Mexico
		Snake gourd	Trichosanthes cucumerina (Trichosanthes augunia)	22	India/Southeast Asia
		Wax gourd (Ash gourd)	Benincasa hispida	24	Java, Japan
		Ivy gourd (Kundru)	Coccinia grandis	24	India
9	Euphorbiaceae	Tapioca / Cassava	Manihot esculenta	36	South America/ Brazil
		Chekurmanis	Sauropus androgynus	36	Indo-Burma
10	Lamiaceae (Labiatae)	Chinese potato	Plectranthus rotundifolius/Coleus parviflorus	2n= 56, 64	Tropical Africa
		Chinese artichoke (Japanese artichoke)10	Stachys affinis	2n= 66-70	China
11	Lauraceae	Bay leaf	Laurus nobilis	42	Mediterranean region
12	Fabaceae (Leguminosae)	Garden pea	Pisum sativum var. hortense	14	Central Asia
		French bean	Phaseolus vulgaris	22	Mexico
		Lima bean	Phaseolus lunatus	22	Guatemala/Tropical America
		Cluster bean	Cyamopsis tetragonolobus	14	India/Africa
		Lab lab bean (Dolichos bean)	Lablab purpureus	22	Africa/India
		Cowpea	Vigna unguiculata	22	Africa
		Sword bean	Canavalia gladiata	22	Tropical Asia/Africa (Old world)
		Jack bean	Canavalia ensiformis	22	South & central America
		Winged bean	Psophocarpus tetragonolobus	18	New Guinea
		Broad bean	Vicia faba	12	Africa (Old world)/Southwest Asia
		Soybean	Glycine max	40	China
		Fenugreek (Methi)	Trigonella foenumgraecum	16	Europe
		Agathi	Sesbania grandiflora	2n=4x=24 (tetraploid)	South East Asia
13	Malvaceae	Okra	Abelmoschus esculentus	130	Africa
14	Moringaceae	Drumstick	Moringa oleifera	28	India
15	Polygonaceae	Rhubarb	Rheum rhabarbarum	2n=2x=44	Central Asia
		Sorrel11	Rumex acetosa	14, 15	Europe/Asia
16	Portulacaceae12	Purslane/Pursley	Portulaca oleracea L.	18,36,45,54
17	Solanaceae	Potato	Solanum tuberosum	2n=2x=48	South America
		Brinjal / Eggplant	Solanum melongena	24	India
		Tomato	Solanum lycopersicum	24	South America
		Chilli / Hot pepper	Capsicum annuum var. longum	24	Mexico
		Bell pepper/Sweet pepper	Capsicum annuum var. grossum	24	Mexico
18	Apiaceae (Umbelliferae)	Carrot	Daucus carota	18	Afghanistan
		Parsley	Petroselinum crispum	44	Mediterranean region
		Celery	Apium graveolens	22	Italy
		Parsnip	Pastinaca sativa	22	Europe
		Coriander	Coriandrum sativum	22	Mediterranean region
		Dill13	Anethum graveolens	22	Mediterranean region
		Skirret	Sisum sisarum	22	China
19	Rutaceae	Curry leaf	Murraya koenigii	18	India/Sri Lanka

Notes:

^*18th century – Refers to the period in which Carl Linnaeus lived and developed his system of plant classification.

^**1753 – Refers specifically to the publication year of Species Plantarum by Linnaeus, associated with the formal establishment of the binomial system of botanical nomenclature.

¹⁴Beetroot is traditionally placed in Chenopodiaceae in many older horticulture textbooks; in modern classification it is included in Amaranthaceae.

¹¹In Rumex acetosa (sorrel), chromosome number differs between sexes: female plants have 2n = 14 (12A + XX), whereas male plants have 2n = 15 (12A + XY₁Y₂).

References:

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21. Tetragonia tetragonioides (Pall.) Kuntze-New Zealand spinach is placed in Aizoaceae; its chromosome number is 2n = 32. PROSEA records it under Aizoaceae with 2n = 32. ¹⁵

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Conclusion.

Botanical classification of vegetable crops provides a systematic understanding of the diversity, relationships and important characteristics of different vegetable crops. It helps in the identification, comparison, grouping and scientific study of crops and provides a foundation for understanding their family, genus, species and other taxonomic relationships. This knowledge is useful for understanding subsequent aspects of vegetable science, including crop improvement, propagation, cultivation and other crop-management practices. The classification presented in this chapter provides a basic and fundamental framework for students before studying the individual classification groups and their detailed descriptions in the following chapters. It is particularly useful for B.Sc. Agriculture, B.Sc. Horticulture, M.Sc. Horticulture and General Agriculture students, including both beginners and students revising their fundamental concepts, and helps in developing a clear conceptual foundation in vegetable science and horticulture.