Classifications
Common names of plants are frequently used, but one plant may have several common words, and the same plant may have different common names in other parts of the world. Botanical names are vital for identifying a plant.
Carl Linacaus, the 18th-century Swedish botanist, developed the system for botanical names, known as the binomial system ( discussed in more detail below). In this system, plants are gathered into particular families according to their flowers, fruits or seeds. A family may have one genus or many.
A genus is a group of related plants within a family. The similarity among members of a genus may or may not be obvious. But taxonomists have determined that, due to certain features, these plants are related and thus classify them in the same genus. Genus names are often derived from Latin or Greek words, mythological figures, or plant characteristics.
The species name is the basic unit of classification. It describes one kind of plant within the genus. Generally speaking, a species is a type of plant with specific characteristics that differentiate it from other members of the genus, which retains these distinctions through successive generations.
In the Linnaean system, each plant is classified using two words in Latin form. The first is the genus, and the second is the specific epithet which is the second part of a species name in binomial nomenclature in any branch of biology. In botany, the term refers to the second part of a botanical name.
Variety and cultivar are two terms that often form part of the second term in a scientific name. Both refer to some unique characteristic of a plant, and it is essential to understand their differences.
Varieties often occur in nature, and most varieties are true to type. The seedlings grown from a variety will also have the same unique characteristic as the parent plant.
Cultivars mean "cultivated variety which does not necessarily propagate true to type. Some cultivars originate as sports or mutations on plants. Other cultivars could be hybrids of two plants.
For a cultivar to propagate true-to-type clones, many cultivars must be propagated vegetatively through cuttings, grafting, and even tissue culture. Propagation by seed usually produces something different from the parent plant.
There are five methods of classifying vegetables:
1. Botanical classification
2. Classification based on hardiness or temperature
3. Classification based on plant part used
4. Classification based on culture
5. Classification based on life cycle
A BOTANICAL CLASSIFICATION – the only method universally accepted.
The classification was developed by the taxonomist Linnaeus, who was the first to give binomial classification in plants and animals.
The classification is based on morphological and cytological similarities and dissimilarities, origin, crossability behaviour, floral biology etc.
The successive levels of morphological relationships are a result of evolution.
Botanical classification involves grouping plants into kingdom, division, sub-division, phylum, sub-phylum, class, sub-class, order, family, genera, species, subspecies, and variety.
The broadest group in which vegetables are discussed is family.
The genus and species constitute the scientific name. Scientific names are accepted worldwide, and there cannot be any confusion as per their nomenclature.
This classification is of little value to the grower. Examples:
· potatoes and tomatoes belong to the same botanical family but have entirely different cultural requirements.
· carrots and radish belong to different botanical families but require similar cultural requirements
All vegetable crops belong to the division Angiospermae. The division Angiospermae has two classes. Class I: Monocotyledoneae Class II: Dicotyledoneae Most vegetables belong to the class Dicotyledoneae.
B CLASSIFICATION BASED ON HARDINESS OR TEMPERATURE
This classification is based on the ability of crop plants to tolerate frost according to the following groupings:
· Hardy crops are those, which can tolerate frost and include winter season/cool season/temperate crops that are adapted to mean monthly temperature of 15-18°C and can be further divided into two sub-groups, hardy or tolerant vegetables and semi-hardy or semi-tolerant vegetables.
· Non-hardy crops or the summer season crops like cucurbits thrive best under high temperatures (20-27°C) and are intolerant to frost.
Warm-season crops can further be divided into two groups: tender or sensitive vegetables and very tender or very sensitive vegetables.
Based on the hardiness, vegetable crops are divided into the following groups.
1. Winter Season Vegetables:
· Hardy/tolerant vegetables include asparagus, broccoli, Brussels sprouts, cabbage, chive, collard, garlic, kale, leek, onion, parsley, pea, radish rhubarb, spinach and turnip.
· Semi-hardy/ semi-tolerant vegetables include carrot, cauliflower, Chinese cabbage, celery, globe artichoke, lettuce, leaf beet, parsnip, and potato.
2 Summer Season Vegetables:
· Tender/ sensitive vegetables—these include chilli, tomato, snap bean and sweet corn.
· Very tender/sensitive vegetables include eggplant, bell pepper, chilli, cluster bean, Lima bean, cucurbits, sweet potato and yam.
C. CLASSIFICATION BASED ON PLANT PART USED
This classification is important from the consumer and post-harvest handling point of view. For example, leafy vegetables are highly perishable and cannot be stored for more extended periods. After harvest, they have to be immediately cooled and stored under ambient temperature conditions to preserve quality.
On the other hand, tubers and bulbs can be stored at room temperature for a considerable period without losing quality.
This classification includes:
1. Leaves; cabbage, lettuce, spinach, leaf beet, etc.
2. Stem; asparagus, celery, cauliflower (hypocotyl branches) etc.
3. Fruits; cucurbits, tomato, eggplant, chilli, bell pepper etc.
4. Pods; snap pea, snow pea, beans, okra etc
5. Flowers; sprouting broccoli, globe artichoke.
6. Roots; radish, turnip, carrot, beetroot, yam, parsnip etc.
7. Bulbs; onion, garlic, leek etc.
8. Tubers; potato, sweetpotato, cassava.
9. Seeds; pea.
D. CLASSIFICATION BASED ON CULTURE
In this classification, all vegetable crops requiring similar cultural requirements are grouped.
Based on their cultural and climatic requirements, vegetables are divided into the following groups; 1. Cole crops; these crops belong to the family Cruciferae and are also called crucifers or Brassicas. These are winter season and transplanted crops.
The crops include cauliflower, cabbage, Chinese cabbage, sprouting broccoli and Brussels sprouts etc.
2. Leafy vegetables; all vegetables belonging to this group are direct-seeded crops and include spinach, leaf beet, coriander, fenugreek, amaranth, Swiss chard etc.
3. Salad vegetables are mainly eaten raw and include lettuce, celery, chicory, and parsley.
4. Root vegetables; these crops have prominent and fleshy underground structures and are direct-sown winter season crops. These include radish, carrot, turnip, beetroot, parsnip, rutabaga etc.
5. Cucurbit crops; these crops belong to Cucurbitaceae, commonly known as the gourd family. The plants have tendrils and produce fleshy fruits. These are direct-seeded summer season crops and include melons, gourds, cucumber, pumpkin and summer squash.
6. Solanaceous crops; belong to Solanaceae, commonly known as the nightshade family and are summer season transplanted crops. These include tomato, chilli, bell pepper and eggplant.
7. Pea and beans (pod vegetables); are legume vegetables and belong to Fabaceae or the pea family. These are directly seeded vegetables and include pea, French bean, Dolichos bean, broad bean, cluster bean, Lima bean, winged bean and cowpea.
8. Bulb vegetables; these are species of Allium and belong to the family Alliaceae. These are winter season crops and include onion, leek, garlic, etc.
9. Perennial vegetables; these crops remain in the field for more than two years and include asparagus, artichoke, Jerusalem artichoke, chayote, ivy gourd and pointed gourd.
10. Tuber vegetables; these include potato, sweet potato, taro, cassava/ tapioca, yams.
E, CLASSIFICATION BASED ON LIFE CYCLE
All vegetables can be classified into three groups: annuals, biennials, and perennials, depending upon the time required to complete their life cycle. Most vegetables are annuals.
1. Annual vegetables complete their life cycle in a single growing season.
2. Biennials require two growing seasons. In one season, they complete their vegetative growth, and in the second season, they complete their reproductive phase.
3. Perennial vegetables grow for more than two years and can be retained for economic yields even up to 15 years.
The examples in the three groups are;
1. Annual vegetables; pea, beans, tomato, okra, eggplant, chilli, bell pepper, cucurbits etc.
2. Biennial vegetables; cole crops, bulb crops, root crops etc.
3. Perennial vegetables. Asparagus, artichoke, Jerusalem artichoke and pointed gourd.
References:
Classification of vegetable crops, Major S Dhaliwal. Ph D Punjab Agricultural University | PAU · Directorate of Research
Complete book of vegetables, herbs and fruit, Biggs M, Mcvicar, Flowerdew, Craft. Kyle books, Craft print International limited.