Vegetables: Biol 1300 Unit 6 PDF

**Biol 1300 Unit 6** **VEGETABLES** **Vegetable** is a \"catch-all\" term, referring to all plant parts (both above-ground and below-ground) exclusive of the fruit. Two broad categories are recognized: \"root\" or below-ground crops, and \"green\" or above-ground crops. The term \"**root crop**\"...

**Biol 1300 Unit 6** **VEGETABLES** **Vegetable** is a \"catch-all\" term, referring to all plant parts (both above-ground and below-ground) exclusive of the fruit. Two broad categories are recognized: \"root\" or below-ground crops, and \"green\" or above-ground crops. The term \"**root crop**\" refers to vegetables in which the harvested portion is dug from the soil; it includes both **true roots** (defined as plant parts whose primary functions is the absorption and conduction of water and nutrients), as well as underground stems that are not true roots (fibrous, less starch, NOT true roots). Most of the economically important true roots are **taproots**, defined as large, swollen true roots that are specialized for storing carbohydrates; examples include the carrot and turnip. In addition to true roots, many plants have underground stems that also store carbohydrates: **Bulbs**: modified stems with basal scale leaves, e.g. onion, garlic. **Rhizomes**: swollen, horizontal underground stems, e.g. ginger, liquorice. **Tubers**: swollen, greatly enlarged rhizome tips, with \"buds\", e.g. potato, yam. **Corms**: enlarged, swollen fleshy stem bases, e.g. water chestnut, taro. They are like bulbs; however, they are not layered like bulbs and bulbs have roots at the bottom (which also sets them apart from tubers). The \"green\" vegetable crops include **all above-ground plant parts *except* for the fruit**. Many above-ground plant parts are harvested for human consumption, including: **Leaves**: e.g. spinach, lettuce. **Stems**: e.g. asparagus (young stem shoots). **Immature flowering heads**: e.g. cauliflower, broccoli, artichoke. **Shoot tips**: e.g. bamboo shoots. **Seedlings**: e.g. malt barley, bean and alfalfa sprouts. **MAJOR ROOT CROPS** **BULBS**: **Onions and relatives** The important food bulbs belong to the genus **Allium** in the monocot **Daffodil (Amaryllidaceae)** family. This includes onions (**A. cepa**), shallots (**A. cepa**), garlic (**A. sativum**), chives (**A. schoenoprasum**), Welsh onions (**A. fistulosum**), and leeks (**A. porrum**). Originating from central Asia, these species have been used by humans for a long time. Their pungent flavor comes from volatile sulfur compounds (allicin) in the plant cells, which cause eye irritation when the bulbs are cut. [The Daffodil family also includes many horticultural plants like daffodils, tulips, and other spring bulbs](https://en.wikipedia.org/wiki/Allium). **TUBERS: Potato and Yams** The most important food tuber is the **potato (Solanum tuberosum)**, a eudicot which belongs to the **Tomato (Solanaceae) Family**. Native to Bolivia and Peru in the Andes Mountains, the potato was domesticated around 7,000 years ago. It was introduced to Europe by the Spaniards in the early 1500s (via Spanish Conquest). Potatoes thrived in the cool summer climate of northern and eastern Europe, quickly becoming a staple starchy food source across much of continental Europe. Fresh potatoes are about 80% water, high in carbohydrates (starch) and some vitamins, but they contain little protein. The potato was introduced to the British Isles by Sir Francis Drake in the early 1600s and became a staple crop by 1800, especially in Ireland. Potatoes are rich in carbohydrates and can be easily propagated vegetatively through the "eyes" of the tubers, thus producing clones. The variety introduced to Ireland was derived from a single cultivar, leading to low genetic variation and resistance. This made the crop highly susceptible to pests and pathogens. In 1845, a severe famine occurred when potato blight (Phytophthora infestans, a fungal water mold affecting tubers and leaves) decimated the crop in 1846-47, resulting in over a million deaths and prompting many to emigrate to North America. It was a wet summer. Numerous monocot yam species are economically important tubers in tropical regions. The yellow and white yams (**Dioscorea cayenensis**) are native to West Africa and are important carbohydrate sources there. The water yam (**Dioscorea alata**), an ancient Asian cultigen, produces tubers up to 20 kg and is widely grown in East Asia and Africa. The cush-cush yam (**Dioscorea trifida**) produces small, yellow tubers and is native to Central America, where it remains an important staple crop. Like potatoes, yams are propagated vegetatively by cutting mature tubers into small pieces. As will be discussed, they are often conflated with sweet potatoes. **CORMS** **Taro** (Colocasia esculenta) is a significant commercial corm, a monocot likely originating from the Indian subcontinent and cultivated in Southeast Asia for millennia. It has spread to all tropical regions, becoming a staple carbohydrate source. Taro thrives in water-saturated soils in tropical climates and must be cooked to remove irritant calcium oxalate crystals. It is prepared similarly to potatoes, and fermented taro paste, known as *poi*, a taro-based porridge, is popular in Hawaii and the South Pacific. **TROPICAL TRUE ROOTS:** **CASSAVA** (Manihot esculenta): Cassava, a eudicot tree also known as tapioca or manioc, is a tropical starchy root crop native to Central and South America. It is a crucial starch source in the tropics, especially in parts of Africa where it accounts for about one-third of total caloric intake. Propagated vegetatively from root and shoot cuttings, cassava root is almost pure starch with minimal protein, vitamins, or minerals. Other foods are required to ensure a healthy diet. It contains poisonous cyanogenic glycosides that must be removed by pulverizing and boiling. Cassava can be made into porridge, flatbread, toasted flour, or fermented into beer. Tapioca, made from mashed cassava to form starch pellets, is used as a thickening agent. **SWEET POTATO** (Ipomoea batatas): The sweet potato (Ipomoea batatas), a eudicot native to Central and South America, was first domesticated around 4,500 years ago. It is a trailing vine propagated from root or stem cuttings. Sweet potatoes are highly nutritious, containing starch, protein, vitamins, and minerals, but they are more delicate due to susceptibility to pathogens (fungal rot) and insect attacks, so they are not grown in high quantity. In North American supermarkets, sweet potatoes are often mistakenly labeled as "yams," though true yams are rarely found in grocery stores. Originally, U.S. producers used the term to differentiate sweet potato from regular potatoes. **TEMPERATE TRUE ROOTS: TAPROOTS** **Biennial** (two-year) species, common in cool-temperate regions (areas with a pronounced winter), produce taproots that store carbohydrates in their first year of growth. The above-ground part dies back in the fall, but the taproot remains underground saving carbohydrates and nutrients. In the second year, the stored carbohydrates and nutrients are used to produce flowers and fruit, after which the plant dies. Humans harvest these taproots in early fall of the first year, utilizing them as a significant source of carbohydrates, vitamins, and minerals (before they are used up in the 2^nd^ year). Most of the economically important temperate taproots are obtained from three plant families: **CARROT (APIACEAE or UMBELLIFERAE) FAMILY**: Examples include the carrot (Daucus carota) and parsnip (Pastinaca sativa). Both are native to Europe and Central Asia and have been cultivated for centuries. The modern orange-coloured carrot cultivar was developed in Holland during the 1600s. The Carrot Family is known mainly as a source of spices, carbohydrates, and herbs. **AMARANTH (AMARANTHACEAE) FAMILY**: Examples include the beet and sugar beet (both varieties of Beta vulgaris). The cultivated beet originated from the wild sea-beet found along the Mediterranean coast. The sugar beet was developed in the late 1700s to reduce European reliance on Caribbean cane sugar, especially during the Napoleonic wars when British naval supremacy disrupted sugar cane shipments to France. Modern sugar beets are large, white taproots containing up to 18% sucrose and are a significant source of table sugar in Europe, China, and the United States. **MUSTARD (BRASSICACEAE OR CRUCIFERAE) FAMILY**: Examples of taproots include the turnip (*Brassica rapa* var. *rapa*) and rutabaga or swede (*Brassica napus var*. *napobrassica*), both of European origin and grown for centuries as reliable winter food sources. They thrive in the cool European climate and are easily stored. The radish (*Raphanus sativus*), native to Eurasia, is another important taproot with many cultivars, including the small, pungent European type (usually red) and the large, white Asian type known as daikon. Other taproots are pungent and processed into spicy condiment pastes: horseradish (*Armoracia rusticana*) from southern Europe and wasabi (*Wasabia japonica*) from Japan. **MAJOR GREEN VEGETABLE CROPS** Green vegetables are obtained from many plant families. Only the most economically important families are discussed here. **MUSTARD (BRASSICACEAE) FAMILY** The Mustard (Crucifer) Family, these eudicots are known for their cold hardiness, making them suitable for growth in north temperate regions. The pungent odor and taste of mustards come from mustard oil glycosides (glucosinolates). This family is significant for providing leafy vegetables in both temperate and tropical areas. Additionally, it includes species that produce seed oils (like canola), animal forages (such as forage beets), condiment seasonings (like mustard and wasabi), and root vegetables (such as turnips). *Brassica oleracea*, a highly mutable species native to Europe, has over many centuries of domestication given rise to several economically important \"green\" vegetables: **Cabbage** (var. capitata): in cabbage, the apical meristem of the primary shoot fails to elongate, and the inner leaves do not expand, producing a tight, rounded head. Cabbages were an important winter food in Europe, since they store easily and can be pickled (to produce sauerkraut or kimchi). **Broccoli** (var. italica): broccoli consists of heads of immature flowering buds together with their associated thick fleshy stems. **Brussels Sprouts** (var. gemmifera): these \"miniature cabbage-heads\" develop from axillary buds at the leaf joints of the primary stem. This varietal arose as a natural mutation in a European cabbage field in the 1750s. **Cauliflower** (var. botrytis): cauliflower is a highly modified head of sterile, abortive flowers. Several cultivars have been developed, varying in both colour (white, yellow, green, purple) and shape (round to pyramidal). **Kohlrabi** (var. gongylodes): this cultivar produces a fleshy, bulbous lower stem that is harvested when young (older stems become woody and fibrous). The outer portion is peeled away, and the tender core eaten. **Kale or Collards** (var. acephala): this leafy form is closest to the wild form of the species. Many cultivars are known. Kale is used in soups and stews and served as a pungent green vegetable. Another highly mutable species indigenous to Europe and Southeast Asia, *Brassica rapa*, has given rise to the turnip (*B. rapa* var. r*apa*) as well as several Asian green vegetables. These include: **Bok choi** (var. chinensis): the whole young plant, consisting of a rosette of leaves and the associated white to greenish fleshy leaf stalks, is used. **Chinese flowering cabbage** (var. parachinensis): the flowering stems, and associated leaves and flower buds, are used. The flowers are bright yellow. **Celery cabbage** (var. pekinensis): a dense head of leaves, like European cabbage but with somewhat elongated (rather than rounded) leaves. **SUNFLOWER (ASTERACEAE) FAMILY** This large eudicot plant family includes many horticultural species like dahlia, marigolds, aster, chrysanthemum, and zinnia, but few economically important green vegetables. The most significant vegetable is **lettuce** (Lactuca sativa), native to the Mediterranean and domesticated around 6,000 years ago. Various lettuce cultivars have been developed, including the heading or iceberg type, loose-leaf types like butter lettuce and oak-leaf lettuce, and the cos or stiff-leaved type like Romaine lettuce. The Sunflower family includes green vegetables like endive *(Cichorium endivia*), which are blanched young shoots grown without light, chicory, with multiple uses like salads and forage, and artichoke (Cynara scolymus), an immature flowering head with the edible part being the artichoke "heart" (receptacle tissue). The sunflower (Helianthus annuus) and safflower (Carthamus tinctorius) produce edible seed oils used in margarines, salad oils, and other prepared food products. Additionally, roasted sunflower seeds are edible and highly nutritious. **CARROT (APIACEAE or UMBELLIFERAE) FAMILY**: The leaf petioles or \"stalks\" of both celery (Apium graveolens) and Florence fennel (Foeniculum vulgare var. azoricum) are used as green vegetables. The bulbous root of a cultivar of celery, known as celeriac, is also used; powdered celeriac is known as celery salt. **AMARANTH/GOOSEROOT (AMARANTHACEAE) FAMILY**: Swiss chard or beet green (Beta vulgaris var. cicla) is a leafy (green vegetable) variety of the beet. Spinach (Spinacea oleracea) is native to Southwest Asia and was introduced to Europe during the Middle Ages. The whole leaves are harvested and eaten either fresh (as a salad) or cooked. Spinach is rich in minerals (particularly iron) and vitamins. **ASPARAGUS/LILY (ASPARAGACEAE) FAMILY**: Asparagus (Asparagus officinalis) is a monocot species that was first cultivated in ancient Egypt, and later by the Greeks and Romans. It regained its popularity in Europe in the 1700s after King Louis XIV of France acquired a taste for blanched asparagus spears (young stem shoots). Green asparagus is harvested from young emergent shoots. White asparagus is obtained by mounding earth around the newly emerging shoots, which prevents them from being exposed to sunlight. This lack of sunlight prevents photosynthesis, resulting in the white color. The shoots are harvested before they emerge from the soil.