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Plants Consumed as Vegetables
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In actuality all plants are vegetables, however, the term is usually reserved for edible plants that store up reserve food in roots, stems, leaves and fruits and that are eaten cooked or raw as salad plants. Vegetables make up a large and varied group of great importance in world commerce. Most vegetables have been in use since antiquity so that their origin is often in doubt. The food value of vegetables is rather low due to the large amount of water present, varying from 70-95 percent. Nevertheless, they rank next to cereals as sources of carbohydrates. This is most often present in the form of starch, but sometimes sugar, pectin and other substances may be present. Except for legumes, proteins are rarely available and fats are stored only in very low amounts. The nutritive value of vegetables increases greatly by the presence of the indispensable mineral salts and vitamins, while the roughage value of the plant tissues aids digestion. It is convenient to classify vegetables as earth vegetables, herbage vegetables and fruit vegetables.
Earth vegetables, or root crops, include all those where the food is stored in underground plant structures. The storage organs may differ morphologically. Some are true roots while others represent modified stems, such as tubers, bulbs, corms and rootstalks. All of these structures are particularly well adapted to storage because of their protected position in the soil. Many wild and cultivated species have fleshy underground parts. These have played an important role in the development of civilization and agriculture second only to cereals and legumes. Since ancient times roots and tubers have provided food for man and livestock. Even though the amount of stored material is less than that in dry fruits and seeds, these are extremely valuable because they are readily digested and have a high-energy content. They do have a high water content that not only reduces the amount of available food but also impairs one’s ability to maintain them in storage. The high bulk also makes it impossible to transport and store them as efficiently as cereals, nuts and legumes. Root crops are an important phase of agriculture worldwide. They are mostly grown both for livestock feed and human consumption. The various earth vegetables may be grouped according to their morphological origin. Only some of the most important species are considered.
Several kinds of beets under cultivation are common beets, sugar beets, chard and mangels. These are all in the same species, Beta vulgaris. They all have been derived from the wild beet, Beta maritima of the seacoasts of the Mediterranean region and southwestern Europe. Beets are biennials that produce the first year a large cluster of leaves from a crown at the tip of a fleshy taproot.
Beta vulgaris var. cicla is a type of beet that was known as early as 300 B.C. At first the roots were used both as a vegetable and in medicine. Finally the tender leaves were favored and under cultivation they have developed and the roots became smaller. Today the chard has large leaves with thick stalks and only slightly enlarged roots.
Mangel Wurzels have developed from chard. They have the roots and lower part of the stem thickened with a crimson, golden or white sap. They were an important livestock feed since the 16th Century, and are now grown extensively in Europe and Canada. Mangels contain 3-8 percent sugar and are fed to livestock either dry or as a silage.
These were developed from mangels, but they are smaller and have higher sugar content. They are used extensively as a source of sugar and their tender leaves are consumed like spinach.
Many varieties of the common beet that differ in size, color, shape, sugar content and time of maturing are grown. Early red beets are most favored. The beets are boiled, pickled or canned and are often used for salads. The leaves of young plants are consumed as beet greens.
Daucus carota has been cultivated since before 100 B.C. It was known to the Romans and Greeks and gradually moved into northern Europe. It was a favorite vegetable in England in the time of Queen Elizabeth and was brought to eastern North America in 1609. From there Amerindians spread it to the rest of America. Carrots are usually biennials but may mature in one year. They pinnately compound leaves. The many varieties differ in shape, color, size and quality and are affected by soil type. A deep sandy loam is best. The roots are harvested in autumn and stored in cellars. Most of the food is stored in the outer cortical portions of the taproot. The central portion of earlier varieties remained woody and unpalatable. Carrots are consumed raw or cooked and may be used to flavor soups and stews. They are also a valuable livestock feed, and are especially favored by horses. The yellow color is carotin, which is sometimes extracted and used to color other food.
Oyster Plant or Salsify, Tragopogon porrifolius, is a hardy biennial with a large fleshy taproot that at times may reach up to one foot in length. It is a composite that when mature has large purple heads with fruits that resemble those of a dandelion. It is native to Southern Europe but is cultivated worldwide and may establish as a weed. The roots are cooked or used as a relish. They have a flavor that resembles oysters.
Pastinaca sativa was used by the early Romans and Greeks and has since spread worldwide. It was represented in nearly all the early herbals. It is native to Europe and reached the West Indies in 1564, Virginia in 1609 and by the 18th Century was being grown widely by Amerindians in North America. The plant has a tendency to escape from cultivation and revert to a primitive growth habit with tough dry roots. Seedlings from the wild forms when moved to favorable environmental conditions gradually resume the cultivated form. Parsnips have a high sugar content and some fat. They are used cooked and for livestock and even for making wine.
Raphanus sativus is an annual or biennial with a fleshy taproot and rosette of small leaves that later are replaced by the erect flowering and fruiting part of the plant. They have been grown since before 100 B.C., but remain close to the ancestral type and often revert to a form with a dry woody root. Radishes are grown worldwide and are esteemed for their pungent flavor. There are many varieties, all differing in size, color and shape of the roots. There are early, summer and winter types and they are frequently forced in hotbeds. Although mostly eaten raw, they may be also cooked.
These are very closely related plants that are sometimes considered as varieties of a single species, Brassica campestris. However, in the Turnip, Brassica rapa, both the root and the lower parts of the stem are fleshy and rough. The texture varies, with the finer ones being used as human food while the coarser types are fed to livestock. Turnips were being grown since 2,000 B.C. and spread from the ancestral home in Europe to other parts of the world. They arrived in Mexico in 1586, Virginia in 1610 and New England in 1628 (Hill 1952). The many varieties differ mainly in the color and shape of the root. Turnips thrive in cool climates and are grown as winter vegetables in the subtropics. The leaves are used for greens and for livestock forage and manuring.
The Rutabaga, or Swedes, Brassica napobrassica, has a larger smooth root with a short neck composed of stem tissue. The flesh is more solid and they are easily stored for long periods. They grow well in northern regions where the cool climate favors the development of the typical sweet flavor. Rutabagas are also used as a livestock feed.
Ipomoea batatas is definitely a native to tropical America where the Amerindians for millennia before the European colonization most likely grew it. There is some mystery about how it became widespread in the tropics of both hemispheres perhaps well before the Christian Era. Thus it serves as an example of probable Pre-Columbian contacts between the hemispheres. The plant is now especially abundant in the South Seas, Japan, China and Indonesia. The sweet potato along with the yam, cassava and taro are indispensable mainstays of the diet in tropical countries. The crop is available throughout the year and grows in every kind of soil.
The plant is a twining, trailing perennial vine with adventitious roots that terminate in swollen tubers. They contain both sugar and starch and some fat. Sandy soil and a warm moist climate are preferred. In North America the Atlantic coastal plain from the Gulf States to New Jersey is the main producing area, with North Carolina, Georgia and Louisiana leading production. The plants are grown as annuals and propagated vegetatively from the roots or vine cuttings. There are two major types grown. One type has a dry, mealy yellow flesh and is preferred in northern areas. A second type, often-misnamed yams, has a more watery, soft, gelatinous flesh that is richer in sugar. This is favored in the South where sweet potatoes are a staple crop and rank next to potatoes in importance. They are used not only as a table vegetable but also for canning, dehydrating, flour manufacture and as a source of starch, glucose syrup and alcohol. They are also used as a livestock feed. The green tops are used for fodder. Their high water content makes them spoil easily.
The genus Dioscorea includes the true yams. Many species exist in the tropics and subtropics worldwide, and they are difficult to distinguish. Dioscorea alata is one of the more common cultivated species. Yams are all climbing vines with large storage roots that often weigh as much as 30-40 pounds and occasionally have aerial tubers. They require a deep soil but are drought resistant. Yams constitute a main food for inhabitants of the tropical regions. They are broiled, baked or ground into flour. Yams are also a valuable livestock feed.
Manihot esculenta is a very important root crop of the tropics. Native to South America it is widely grown in all tropical and subtropical areas. There are over 155 varieties most of which are used locally for food. Two main groups are the bitter cassavas and the sweet cassavas. They are shrubby perennials with stems reaching a height of 9 feet. They have 3-7 deeply parted leaves and roots that terminate in large tubers. All varieties contain a glucoside similar to prussic acid that is poisonous. However, only a slight amount of heat is required to drive off the volatile acid and to render the flesh harmless. Other names for Cassava are Manioc, Mandioc and Yuca.
The crop is grown easily with a minimum of labor. Stem cuttings of 6-10 in long pieces propagate it. The plant matures in 6-12 months and the yield is great. One acre can produce more than 7 tons of cassava tubers. The roots of a single plant can weight 25-50 pounds.
The tubers are consumed cooked or raw. Sweet cassavas are usually boiled. A flour known as Farinha is prepared by peeling, washing and scraping or grating the tubers and then placing the material in a bag or press where the liquids are removed. After drying and sifting the meal is baked into thin cakes known as Cassava Bread. This has a high food value and replaces wheat bread in the diet. The poisonous milky juice is concentrated to a thick consistency by boiling and constitutes Cassareep or West Indian Pepper Pot that is used for making sauces. Raw cassava starch has healing qualities and is fermented to make an alcoholic beverage. It is also a livestock feed and may be used for sizing and laundry work.
Raw cassava is used to make Tapioca. The roots are peeled and grated and the milky fluids expressed. The starchy material is then soaked in water for several days, is kneaded and finally strained to remove any fibers and impurities. After sifting and drying it is gently heated on hot iron plates. This partially cooks the starch and causes it to ball up into little round lumps, which are the tapioca of commerce.
Helianthus tuberosus is native to North America where Amerindians have cultivated it for centuries. It is a hardy perennial sunflower 6-12 ft tall. The name “sunflower” comes from the Italian word for sunflower, girasole. The plant was introduced into Europe in 1616 and has been cultivated more extensively there than in the West. The plant is adapted to a wide variety of climates but grows best in more temperate areas. The tubers somewhat resemble potatoes but with larger eyes. They are cooked, pickled, or consumed raw. The carbohydrate is in the form of inulin that is suited for diabetics and is also used as a source of levulose and industrial alcohol. Sunchokes are also grown as forage crop and weed eradicator.
Solanum tuberosum is the white or Irish Potato that is now a mainstay worldwide. It is a native American species that was being cultivated from Chile to New Granada at the time that the Spanish explorers reached America. The first published mention of the potato was in 1553 in Pedro de Leon’s “Chronica del Peru,” while the first illustration appeared in Gerard’s Herbal in 1633 (Hill 1952). The potato reached Europe via Spain soon after 1580 and by the end of the 17th Century was being grown all over Europe and the British Isles. Irish immigrants brought the potato to New England in 1719 although it had been brought to Virginia and the Carolinas earlier.
Potatoes are erect, branching and somewhat spreading annuals from 2-3 ft. tall. They have pinnately compound leaves, fine fibrous roots and abundant rhizomes that are swollen at the tip to form the familiar tubers. The flowers are yellow, white or purple with a tubular corolla. The fruit is a small brownish-green or purple inedible berry.
Potatoes are adapted to many soils and climates. They are grown worldwide except in the lower tropical regions. They are hardy and mature rapidly and can be grown as far north as 60 deg. N. Latitude and at altitudes up to 8,000 ft. The best environment is a cool moist climate with a mean annual temperature of 40-50 deg. Fahrenheit and a rich light soil.
Propagation is usually vegetatively by means of tubers or parts of tubers the so-called “seed potatoes.” However, they may be grown from seed. The more than 520 varieties in cultivation have been obtained by selection and hybridization and by the utilization of mutations that are frequent. The essential parts of the seed potatoes used for propagation are the eyes. These are really groups of buds located in the axils of aborted leaves. There is usually a central bud in each eye surrounded by smaller lateral buds. The eyes are more abundant toward the apex of the tuber. Pieces of the tubers are cut at right angles to the main axis so as to remove the inhibiting effect of the terminal bud. The larger the piece the more vigorous is the vegetative growth, which results in a greater yield. The tubers have a rest period of several weeks after they have matured during which they will not sprout. This is a period of after ripening in which several physiological changes occur. The duration of the rest period can be controlled by the use of cold and by various gases and chemicals.
There are several regions in the tubers. These include the skin or periderm that varies in color, texture and thickness; the narrow cortex, a dense area with small starch cells; a ring of fibro vascular bundles; the external medulla, which contains most of the starch; and the internal medulla, which has a greater percentage of water and less starch. Branches of the internal medulla extend outward toward each eye. In all these areas the starch occurs in typical oval grains of different sizes in thin-walled parenchyma cells. The mealiness of the potato is due to the swelling of the grains and the rupturing of the cell walls. When the external layers are low in starch the walls do not burst and the tuber becomes soggy. Potatoes contain about 78 percent water, 18 percent carbohydrates, including some sugar as well as starch, 2 percent proteins, 0.1 percent fat, and 1 percent potash. They are well adapted to storage in a cool dark place. The water loss over winter amounts to about 11 percent.
Potatoes are grown over a wider area of the world than any other crop. The commercial production of potatoes is usually concentrated in areas where both the climate and market conditions are most favorable. The larger tubers are used mainly for human consumption while small tubers are converted into starch and industrial alcohol and also fed to livestock.
In the high Andes Mountain areas of South America there are other species of Solanum cultivated by the natives. Additionally there are other tubers that have been important food plants for centuries in this area. The most important is Oca, Oxalis tuberosa, an upright succulent herb with trifoliate leaves and orange yellow flowers. Several varieties are grown. The tubers contain calcium oxylate crystals and must be mellowed in the sun before they are consumed. Ulluca or Melloco, Ullucus tuberosus, is second in importance. The tubers appear as small potatoes. The plants are resistant to frost and give a high yield. The Ańu, Tropaeolum tuberosum, is a twining plant related to the garden nasturtium is of lesser importance.
Arracacha, Arracacia xanthorrhiza, is native to the Andes region. It is a robust herb with large fleshy roots that is widely cultivated as a starchy food. Achira, Canna edulis, has an edible tuber that is also one of the sources of Arrowroot starch. Yam Bean, Pachyrrhizus erosus, has tubers that are consumed either cooked or raw.
These are next to yams in importance in Asia and they constitute the staple food for the masses. Over 1,020 varieties are grown. They are among the few edible aroids and belong to the genus Colocasia. Taros and dasheens are similar and are sometimes considered as variants of a single species. There is no erect stem but a cluster of large leaves from 4-6 ft. long.
Taro, Colocasia antiquorum, is native to Southeastern Asia from where it spread throughout Polynesia and the Pacific area. The plant has huge peltate leaves and has been cultivated for so long that it never flowers. The tops of the corms are used to propagate taro. A wet rich soil and a long season are required. The yield is high and the starch is of good quality and readily digested. Hill (1952) noted that there was no word for indigestion in the ancient Hawaiian language. Taros are baked or broiled to destroy the acrid calcium oxylate crystals in the raw tubers. A principal food of Polynesia is Poi, a thin pasty mass of taro starch. It has a slight acid taste and is palatable. It is frequently made into cakes, baked or toasted.
Dasheen, Colocasia esculenta, has large tubers with smaller ones on the side. The flesh is mealy with a nutty flavor and ahs more carbohydrates and proteins than potatoes. Dasheens were grown as a commercial crop in the southern United States since 1913 where the tubers were used as a substitute for potatoes.
These are some of the oldest of the root crops and they are found only in tropical America. The most common species is Xanthosma sagittifolium. Yautias resemble taros to which they are closely related. But they are taller often reaching a height of 7-8 ft., with arrow-shaped leaves. They produce both corms and tubers. The plants are common in the West Indies, especially in Puerto Rico, and many varieties are grown. The tubers are twice as nutritious as the potato.
Allium cepa is the main food plant in which the food is stored in a bulb. It is ancient, being known before 2,000 B.C. There are no wild onions. It probably originated in Southern Asia or the Mediterranean region. It has long been esteemed in India and China for its flavor. It was worshiped in Egypt before the Christian era and it also played a part in the Druid rites. Onions are cultivated over a large part of temperate and tropical climates. They prefer cool moist climates with a sandy soil. They are started from seeds or sets, small bulblets that are produced instead of flowers. Onions have to be dried and cured before they are stored in order to develop the typical flavor and taste. These are due to an acrid volatile oil, allyl sulphide. They are used both as vegetables and flavoring agents. There are more than 255 species of Allium known, some of which are native to boreal America. Many occur as weeds. The most common cultivated forms are garlic, chives, leeks, shallots and the true onions.
Garlic, Allium sativum, is a perennial with narrow flat leaves and several small egg-shaped bulbs, called cloves, enclosed in a white skin. The inflorescences produce both seeds and bulblets. The latter together with the cloves and the leaves have been used since ancient times for flavoring salads, soups and meats. Garlic also possesses bactericidal and antiseptic properties.
Leek, Allium porrum, is also an ancient plant. It is a hardy perennial of the Mediterranean region with thick, flat, broad leaves and small bulbs. The bases of the leaves are mild flavored and edible and they are often blanched like asparagus. They are used for flavoring stews and soups.
Chives, Allium schoenoprasum, have hollow and cylindrical leaves with small clustered bulbs and dense umbels of rose-colored flowers. They are hardy perennials that grow in dense clumps. The young leaves and bulbs are for seasoning.
Shallots, Allium ascalonicum also have cylindrical hollow leaves but the plants are not cespitose. They are perennials with large clustered leaves that are widely used in pickling. The leaves are short and shaped like an awl.
True Onions, Allium cepa, are biennials with a single large bulb and long, hollow cylindrical leaves. A single leafless scape arises from each bulb and may attain a height of 2-3 ft. There are numerous small flowers. Many different forms occur with either round, flat, white or colored bulbs. Spanish and Bermuda onions are large and mild flavored. The early colonists brought onions to America and division, bulblets and seeds propagate them. They are used for flavoring, as a vegetable, for pickles and in medicine.
These plants have nutrient materials stored in structures that develop above the ground. They are the pot herbs and salad plants. Many parts of the shoot system of the plant may be utilized for storage. Leaves are used in cabbage, spinach, kale and lettuce; stems are used in kohlrabi and asparagus; buds are used in Brussels sprouts; leafstalks are used in rhubarb and celery; and immature flowers and flower stalks are used in broccoli and cauliflower. The food value and chemical make-up of herbage vegetables are similar to those of the earth vegetables. However, there is more water and therefore a smaller amount of carbohydrate. They contain more proteins because the leaves are the chemical plants of the plant, and also a large amount of mineral salts and vitamins that make them an essential part of the human diet. There is also the value gained from plant fiber.
Cynara scolymus is indigenous to the Mediterranean region and Canary Islands. The artichoke plant resembles a thistle in size and growth habit. Flower stalks end in globular inflorescences with many subtending involueral bracts. The immature heads and the fleshy bases of the leaves and the thickened receptacle are consumed usually after cooking. Artichokes prefer low ground near seacoasts. They are widely cultivated in Central and Southern Europe and California. Pickled artichoke hearts are a popular item.
Asparagus officinalis is indigenous to temperate Europe and Western Asia and may still be seen growing wild in that region. I has been prized since Roman times and widely grown throughout Europe. It was introduced to America with the first Post-Columbian colonists. it ahs perennial roots that sent up an erect branching stem several feet tall. It has modified branches called cladophylls, which is typical of the entire genus, including the asparagus fern. The axillary flowers are small and the fruit is a berry. The new shoots are juicy and succulent, and these are the asparagus that is consumed. The plant becomes bushy and woody if the shoots are allowed to develop. it thrives best in fertile well-drained soil in humid temperate climates with an abundance of sunshine. it can be grown from seed or from one year-old crowns. The plant may live for 15-20 years. The shoots are consumed either green or blanched. For best flavor asparagus should be cooked within 12 hours of picking. The food value is low and the water content is about 94 percent, but there is more protein present than in most vegetables. Sometimes the pulp may be dried or canned as a paste. Asparagus also has a medicinal value.
Cabbage, Brassica oleracea, is an ancient and very important herbage vegetable. The wild ancestor is the colewort, a stout weedy perennial of the coastal areas of Great Britain and Southwestern Europe. A great variety of cultivated forms have been produced by selection from this plant. A Mediterranean type climate is most suitable, but cabbage will grom from the arctic to the subtropics. Cultivation is very ancient, at least since 2,500 B.C.. Several varieties were known to the Greeks and Romans (e.g., true cabbage, broccoli, cauliflower). it became an important plant in Scotland and Ireland at an early date. Today the plants are grown worldwide except in the low tropics. Cabbage contains the antiscorbutic Vitaminn C and is also rich in sulfur. It is the most varied of all cultivated plants. The most common forms include the collards or kales, Brussels sprouts, head cabbage, cauliflower, broccoli and kohlrabi. In kale and Brussels sprouts the stem of the first year is elongated while in the others it is very short
Brassica oleracea var. acephala is erect and branching. These plants are also known as Borecole or Marrow Cabbage and they are very close to the wild form. They have many large broad leaves that are used as a boiled green vegetable or livestock feed.. The plants are resistant to cold, heat and drought. Giant cabbage kales of England may rach a height of 8-9 ft. and the stout stems can be used for rafters or canes.
Brassica oleracea var. gemmifera has the axillary buds on the erect stem developing into little heads. These miniature cabbages are the consumed vegetable. Both tall and dwarf forms occur. Brussels sprouts are cool-season plants and are more tender and delicate than common cabbage.
Brassica oleracea var. capitata is the familiar cabbage with a short stem and a great mass of thick overlapping leaves that form a head. The older leaves surround the younger, smaller and more tender leaves and the miniature stem, so that when sectioned it resembles a huge bud. There are many varieties that hive either smooth or curled leaves. The latter are the Savoy cabbages with excellent flavor. Both green and red cabbages are grown. Cabbage is adapted to cool climates and can be grown on heavy soil. The plant is very old and was introduced into England by the Romans. Cabbage contains 91 percent water with some sugar and starch, considerable protein and valuable lime salts. It is consumed ray as Slaw or cooked. Steaming is preferred to boiling because the nutrients are retained. Sauerkraut is cabbage fermented in its own juice together with salt. Lactic acid bacteria act on the sugar to produce lactic acid that is responsible for the sour taste. Sauerkraut originated in Asia and spread westward throughout Europe in early times.
Brassica oleracea var. gongylodes does not form a head, but the short stem is transformed into a juicy mass, which stands out of the ground. It is large, spherical and turnip like, white or purple in color with large leaf scars. Kohlrabi is an early spring or fall crop as it does not do well in hot weather. It has been considered a distinct species, Brassica caulorapa.
In both of these forms there is a short erect stem with an undeveloped inflorescence. In Cauliflower he whole inflorescence forms a large head of aborted flowers on thick hypertrophied branches. The leaves are frequently tied around the mass of flowers to keep them white. In Broccoli the heads are smaller and the leaves larger and the whole plant remains green. These are ancient cultivated plants that are more delicate and easier to digest than cabbage.
Apium graveolens var. dulce is indigenous to temperate Europe from England to Asia Minor. Wild plants are tough and rank bear an acrid and poisonous juice. it grows in ditches, marshes and other wet places. Under cultivation it is a biennial that forms a fleshy root and clump of compound leaves with long leafstalks. The stalks are large and succulent and their quality is improved by blanching before harvest. This is accomplished by placing boards, soil or paper around them to shut out light and so to prevent chlorophyll from developing. Celery requires a rich sandy loam and lost of water. It is grown as a winter crop in the subtropics and as a summer crop in temperate regions.
Celery was originally grown in the Old World for its foliage that was used for flavoring and as a garnish and for medicinal purposes. The roots are often boiled. The outer stalks that are too tough to consume are used as a basis for cream of celery soup. Celery seeds are grown to be used as Savory. The larger turniplike roots of a European variety, Celeriac (Apium graveolens var. rapaceum) are used for flavoring and soups.
Chicory, Cichorium intybus, and Endive, C. endivia, have been cultivated since the Middle Ages but still retain their wild appearance and have not been greatly modified from the wild plants.
Chicory is a perennial with a long taproot, coarse branching stem and abundant basal leaves. The flowers are generally blue. This plant is native to Europe but has escaped cultivation in America. it is used as a salad plant or for greens. The roasted root is an important adulterant of coffee
Endive, an annual or biennial, is indigenous to India and was a favorite salad plant of the ancient Egyptians and Greeks. The young basal leaves often have curled margins and are used in salad. They may be blanched before use.
Lactuca sativa is native to Southern Europe and Western Asia. It is a descendent of the wild lettuce, Lactuca scariola, a common weed of roadsides and waste land in both Hemispheres. Three varieties of lettuce were cultivated by the ancient Greeks, and Persian kings used it before 300 B.C. (Hill 1952). The Moors developed many varieties among them the Romaine Lettuce. The plant has a basal rosette of leaves and later in the season a stalk with flowers and fruits. Lettuce has a milky juice. it has little food value except for vitamins and iron salts. There are several hundred varieties grown. The plant thrives in sandy or loamy soil and requires cool weather and partial shade in summer. Principal varieties include head lettuce, cos, romaine and leaf lettuce.
Rheum rhaponticum has succulent acid leafstalks. Native to Asia it is a perennial with large rhizomes and it produces a number of very large leaves early in the season. Later an elongated flower stalk develops that bears dense masses of tiny white flowers. It is widely cultivated as a food plant and occasionally as an ornamental, in temperate regions of Europe and America. Rhubarb is nearly 95 percent water with a little sugar and fat and salts of oxalic and malic acid. The stems are used for pies and sauces and a wine is made from the juice. The leaves should be avoided as they are poisonous.
Spinacia oleracea is a common herbage vegetable used for greens. Native to Southwestern Asia it is widely cultivated in cool regions where there is an abundance of wat er. It produces a large number of basal leaves early in the season, and later the flowering portion. Spinach is an annual that occurs as several forms. It is used as a pot herb and cooked vegetable.
Chinese Cabbage, Brassica pekinensis and B. chinensis, is an annual plant used for greens and salads. Dandelion, Taraxacum officinale, is popular for its greens collected in the wild state. Water Cress, Nasturtium officinale, is an aquatic perennial that is used for salads. New Zealand Spinach, Tetragona expansa, is a warm-weather crop where only the tender young leaves are used. Tampala, Amaranthus gangeticus, is a kind of lettuce with both red and green varieties. Additionally, there are many wild species used by local residents for pot herbs, especially in springtime. The leaves of turnips, beets and mustard are also favored.
These are technically fruits but are consumed as vegetables, many requiring cooking. Most of them resemble other vegetables, the avocado being an exception.
Persea americana, the avocado or alligator pear, is a species with many different varieties occurring from Mexico to South America. The brownish-green pear-shaped fruit varies from 4-6 in. in length, is actually a one-seeded berry. The pulp surrounding the large seed has a buttery consistency and contains up to 30 percent fat, considerable carbohydrate and more proteins than any other fruit. The vitamin content is also very high. There are over 500 varieties and three major races: the Guatemalan, West Indian and Mexican. These differ in shape, size and hardiness as well as fat content. A few dwarf varieties such as Gwen and Little Cotto have been developed. Avocados have been used since ancient times in America and are consumed either fresh or cooked. The Guacamole of Mexico is a favorite dish that combines avocado flesh with chile pepper, garlic, lime juice and other spices.
Breadfruit, Artocarpus altilis, has been a valuable human food in tropical countries of the world. It has been cultivated since antiquity. This is a very handsome tree with deeply incised leaves that reaches a height of 40-60 ft. The fruits are prickly and about the size of a melon. They are brownish yellow when ripe with a fibrous yellow pulp. These are often borne in small clusters. The fruit is consumed fresh or cooked. It may be broiled, baked, fried roasted or ground up and used for bread. During the months when the fruit is not available a paste that has been stored is used. There are over 110 varieties of breadfruit, some being seedless. There are few fruits trees that give a greater yield. An 8-year old tree may produce 700-800 fruits. The carbohydrate content is very high.
Jackfruit, Artocarpus heterophyllus, is similar. an Indo-Malayan species, it is now widely dispersed in tropical countries. It is also a handsome tree that may reach of height of 60-70 ft. The leaves are entire and huge fruits, 1-2 ft. long weighting 20-40 lbs. are borne on the trunk.
Sechium edule is a trailing vine native to tropical America. It produces gourd like fruit that is used as a vegetable. The fruits are actually pepos, berries with a spongy pulp and a hard firm rind. Chayote is a perennial with large tuberous roots. Both fruits and tubers were used since ancient times in Neotropical America. The plants grow vigorously and have a prolific yield. Both the tubers and young and old fruits are consumed, but the foliage can be used as greens or forage and the young shoots are a substitute for asparagus. The flavor varies with the age of the fruit. The straw is valuable for making hats and baskets. It is a good bee plant and is sometimes planted for ornamental purposes.
Cucumis sativus is a gourd fruit that is believed to have originated in India. It was cultivated since before 2,000 B.C. Reference to cucumber is found in the earliest writings of Hebrews, Egyptians and Greeks. The plant reached Europe by the 17th Century. it is a rough-stemmed trailing vine with yellow axillary flowers and round to elongated prickly fruits. The water content is around 96 percent. Cucumbers are consumed raw, pickled or cooked
Pickles are made from small cucumbers or special varieties. The fruits are soaked in brine and treated with boiling vinegar. Sometimes dill and other spices are added to provide a distinctive flavor.
Solanum melongena is indigenous in India but is widely grown worldwide. Several taxonomic varieties exist. The plant is an erect branching herb that may reach a few feet in height. The fruit is a berry that varies from large ovoid to slender, whitish or purple. Cultivation is as an annual that requires a high temperature. The fruit is cut into slices and fried or broiled.
Hibiscus esculentus is native to tropical Africa. It was being cultivated in Europe by 1216 A.D. The plant is a stout annual that resembles cotton in its habit. The young pods are mucilaginous and are favored in soups under the name Gumbo, the Spanish word for okra. It may be cooked in several ways. Young pods when cooked resemble asparagus in flavor. It is frequently dried or canned. The stems and mature pods yield a fiber that is used to make paper and for textiles.
These are gourd fruits native to America that belong to the genus Cucurbita. The several cultivated species have never been found in the wild state and have been important in the diet of Amerindians since antiquity. There had been some speculation that the genus originated in Africa. At least two varieties were grown in Peru as early as 2,000 B.C. Cucurbita pepo was cultivated by North American peoples also since about 2,000 B.C. and Cucurbita moschata by 312 A.D.
These plants are coarse annual vines with large yellow flowers and fruits that rest on the ground surface. The many varieties are insect pollinated and readily cross. For example, they may be grown in glasshouses in the presence of mosquito colonies maintained in tanks of water. Immature fruits are used as fresh vegetables stewed, boiled or fried, while mature fruit5s are baked, canned or fed to livestock. The seeds are high in fats and proteins and can be utilized as a source of an edible vegetable oil. Pumpkin seeds that are fried in oil and salted are available as Pepitos.
Cucurbita pepo includes the field pumpkins that are used for pies, canning and livestock feed; the summer or crookneck squashes, acorn squashes, scallop squashes, pattypans or cymlings; zucchinis; vegetable marrows; and small inedible gourds grown for ornamental purposes. Cucurbita moschata includes autumn and winter varieties such as the butternut squash. Cucurbita mixta includes the cushaw squashes and some gourds. Cucurbita maxima include such autumn and winter squashes as the buttercup, mammoth, Hubbard and turban. Cucurbita ficifolia is the only perennial species that was cultivated by Amerindians in Neotropical America since ancient times and was undoubtedly used also to make containers. This species in clues the Malabar and other ornamental gourds.
Lycopersicon esculentum is thought to have originated in the Peru-Ecuador area, from which it spread northward in Pre-Columbian times to Mexico where it became domesticated. Tomato was transported to Europe by Spanish explorers. it was originally considered to be poisonous and was grown for ornamental purposes only under the names of Tomatl, Love Apple or Pomme d’Amour.
Tomatoes are coarse, branching, erect or trailing herbs with a true berry for fruit. They differ in habit depending on environmental conditions. There are over 180 varieties among which several taxonomic groups may exist. They are perennials in warmer regions but generally are grown as annuals. Tomatoes are consumed raw or cooked and in preserves. They are particularly high in vitamins. Only the pulp retains the characteristic flavor. The waste consisting of skins, cores, seeds and unripe parts are used to extract a fixed oil that can be used for food, soap or as a drying oil. The oil cake is valuable livestock feed. Ripe tomatoes are also used for sauces, ketchup, and tomato juice and tomato paste. Green tomatoes are used for pickles and preserves or are fried.
Peppers belonging to the genus Capsicum are increasingly used as vegetables instead of only as a spice. However, they are considered further in the section, Spices and Other Flavoring Substances
Olives, which are frequently consumed as vegetables in salads and cooked dishes, are discussed under, “Fruits of Tropical & Subtropical Regions.”