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|Cucurbita fruits come in an assortment of colors and sizes|
|Cucurbita fruits come in an assortment of colors and sizes|
Cucurbita (Latin for gourd) is a genus in the gourd family Cucurbitaceae native to and originally cultivated in the Andes and Mesoamerica. The Cucurbita genus is an important source of human food and is used for other purposes such as beverages, medicine, oil, and detergent. Some Cucurbita species were brought to Europe after the discovery of America and are now used in many parts of the world. The plants, referred to as squash, pumpkin or gourd depending on species, variety and local parlance, are grown for their edible fruits and seeds. Real (bottle-)gourds, used as utensils or vessels, belong to the genus Lagenaria and are native to Africa. Lagenaria are in the same family and subfamily as Cucurbita, but in different tribes.
There are five domesticated species: Cucurbita argyrosperma, C. ficifolia, C. maxima, C. moschata, and C. pepo. C. pepo includes varieties of both winter squash and summer squash, and C. moschata can be used as winter squash because the full-grown fruits can be stored for months. There is no universal agreement on how to handle the taxonomic treatment of the genus, with the number of species being listed varying from 13–30. There is uncertainty as to the ancestors of some species.
Most Cucurbita species are vines that grow several meters in length, have yellow or orange flowers, and may have tendrils. Non-vining cultivars of C. pepo have been developed. There are two types of flowers on a plant, the female flowers that produce the fruit, and the male flowers that produce pollen. Many North and Central American species are visited by specialist pollinators in the apid group, but other insects including honey bees also visit.
The Cucurbita genus is an important source of human food and the fruits are good sources of several nutrients such as vitamin A, vitamin C, dietary fiber, niacin, folic acid, and iron. In addition, they are free of fat and cholesterol. The plants also contain the toxins cucurmosin and cucurbitacin. Medical uses of the plant include treating skin conditions and improving visual acuity.
Most Cucurbita species are climbing annual vines and are mesophytes (requiring adequate water), while the perennials grow in tropical zones and are xerophytes (tolerating dry conditions). The plant stem can grow 5 to 15 meters (16 to 49 ft) and produces tendrils that help it climb adjacent plants and structures or along the ground. Most species do not readily root from the nodes; Cucurbita ficifolia and the 4 cultivated mesophytes are a notable exception. The vine of the perennial Cucurbita can become semiwoody if left to grow. There is wide variation in size, shape, and color among Cucurbita fruits, even within a single species. C. ficifolia is an exception to this, being highly uniform in appearance. The morphological differences in the species C. pepo and C. maxima are so vast that its various subspecies and cultivars have been misidentified as totally separate species.
The typical cultivated Cucurbita species has five-lobed or palmately divided (radiating from the base) leaves having long petioles; with the leaves alternately arranged on the stem. The stems in some but not all species are angular. All of the above-ground parts may be hairy with various types of trichomes, and sometimes these are hardened and sharp. Tendrils grow from each node, and are spring-like; in some species the tendrils may branch. There are male (staminate) and female (pistillate) flowers (unisexual flowers) on a single plant (monoecious), and these grow singly, appearing from the leaf axils. Flowers have five fused yellow to orange petals (the corolla) and a green bell-shaped calyx. Male flowers in Cucurbitaceae generally have five stamens, but in Cucurbita there are only three, and their anthers are joined together so that there appears to be one. Female flowers have thick pedicels, and an inferior ovary with 3–5 stigmas that each have two lobes. C. argyrosperma has ovate-cordate leaves and the corollas of its female flowers are larger than the male flowers. The shape of C. pepo leaves varies widely; its female flowers have a small calyx. C. moschata plants can have light or dense pubescence. The calyx of its male flowers is comparatively short. C. ficifolia leaves are slightly angular and have light pubescence. Its female flowers have noticeably larger corollas than the male flowers. The leaves of all four of these species may or may not have white spots on their leaves.
Botanists classify the Cucurbita fruit as a pepo, which is a special type of berry derived from an inferior ovary, with a thick outer wall or rind formed from hypanthium tissue fused to the exocarp. The fleshy interior is composed of mesocarp and endocarp. The term "pepo" is used primarily for Cucurbitaceae fruits, where this fruit type is common, but the fruits of Passiflora and Carica are sometimes considered pepos. Cucurbita fruits are large and fleshy. Seeds are attached to the ovary wall (parietal placentation) and not to the center. Seeds are large and fairly flat with an embryo which has two rather large cotyledons. Wild fruit specimens can be as small as 4 centimeters (1.6 in), but certain domesticated specimens can weigh well over 300 kilograms (660 lb). The current world record was set by Ron Wallace of Greene, Rhode Island with a 911.2 kilograms (2,009 lb) Atlantic Giant pumpkin.
Many North and Central American species are visited by specialist pollinators in the apid group Eucerini, especially the genera Peponapis and Xenoglossa, and these squash bees can be crucial to the flowers producing fruit after pollination. Competitively grown specimens are often hand-pollinated to maximize the number of seeds in the fruit, which increases the fruit size (an effect called xenia); this pollination requires proper technique. Parthenocarpy is known to occur in certain cultivars of C. pepo.
The plant hormone ethylene promotes the production of female flowers. When a plant already has fruit, new female flowers are inhibited, and male flowers are more frequent, an effect that appears to be due to reduced natural ethylene production within the plant stem. Ethephon, a plant growth regulator product that is converted to ethylene after metabolism by the plant, can be used to increase fruit and seed production. Ethylene and the hormone auxin are key in fruit set and development. The most critical factors in flowering and fruit set are physiological, not climatic, factors. If a fruit is developing, then subsequent female flowers on the plant are less likely to mature, a phenomenon called "first-fruit dominance".
Gibberellin produced in the stamens is a plant hormone essential for the development of all parts of the male flowers, but the development of female flowers is not yet understood. Gibberellin is also involved in other developmental processes of plants such as seed and stem growth.
Seed germination in some species of Cucurbita has been directly linked to embryo axis weight and reserve protein. Maximum seed germination in C. moschata occurs 45 days after anthesis. Seed weight is at its maximum 75 days after germination. Some varieties of C. pepo germinate best with eight hours of sunlight daily and a planting depth of 1.2 centimeters (0.47 in). Seeds planted deeper than 12.5 centimeters (4.9 in) are not likely to germinate. C. foetidissima seeds have a 90% germination rate in pH 8 soil. Plants younger than 19 days old are not able to sprout from the roots after removing the shoots. Over 90% of plants sprout after 29 days from planting.
High levels of pollen load are known to produce more seeds in fruits, faster and more likely seed germination, larger fruits, greater likelihood of fruit maturation, more plant biomass, and larger stems. Various combinations of light and mineral nutrients have a significant effect during the various stages of plant growth. These effects vary significantly between the different species of Cucurbita. Phytate forms in seeds tissues into spherical crystalline intrusions in protein bodies called globoids. The nutrients in globoids are eventually used completely during seedling growth. Heavy metal contamination, including cadmium, has a significant negative impact on plant growth. Sterols are critical to the plant life cycle of Cucurbita and stigmastadienol is the most critical of them. More study is needed on sterol biosynthesis. Sterol levels fluctuate during the plant life cycle, such as decreasing at the onset of flowering. Cucurbita plants grown in the spring tend to grow larger than those grown in the autumn.
The ancestral species of the genus Cucurbita were present in the Americas before the arrival of humans, and all species are native to the New World since the early development of agriculture. The likely center of origin is southern Mexico and then spreading south into South America, largely in what is now known as Mesoamerica, and north to what is now the southwestern United States. Evolutionarily speaking, the genus is relatively recent in origin, and no species within the genus is genetically isolated from all the other species. Cucurbita moschata acts as the genetic bridge within the genus. The genus was part of the culture of almost every native peoples group from southern South America to southern Canada. Modern-day cultivated Cucurbita are not found in the wild. Genetic studies of the mitochondrial gene nad1 show there were at least six independent domestication events of Cucurbita separating domestic species from their wild ancestors. Species native to North America include C. digitata (calabazilla), and C. foetidissima (buffalo gourd), C. palmata (coyote melon), and C. pepo. Every species of Cucurbita has 20 pairs of chromosomes. Some species, such as C. digitata and C. ficifolia, are referred to as gourds, but the real (bottle-)gourds, used as utensils or vessels, belong to the genus Lagenaria and are native to Africa. Lagenaria are in the same family and subfamily as Cucurbita, but different tribes.
The earliest known evidence of the domestication of Cucurbita dates back 8,000–10,000 years ago, predating the domestication of other crops such as maize and beans in the region by about 4,000 years. This evidence was found in the Guilá Naquitz cave in Oaxaca, Mexico, during a series of excavations in the 1960s and 1970s, possibly beginning in 1959. Later, more accurate, dating using accelerator mass spectrometers provided more specific dates. Solid evidence of domesticated Cucurbita pepo was found in the Guilá Naquitz cave in the form of increasing rind thickness and larger peduncles in the newer stratification layers of the cave. By circa 8,000 years BP the C. pepo peduncles found are consistently more than 10 millimeters (0.39 in) thick. Wild Cucurbita peduncles are always below this 10 mm barrier. Changes in fruit shape and color indicate that intentional breeding of C. pepo had occurred by no later than 8,000 years BP. During the same time frame, average rind thickness increased from 0.84 millimeters (0.033 in) to 1.15 millimeters (0.045 in).
The process of domesticating the squashes took place over 5,000–6,500 years in Mesoamerica. Squash was domesticated first, followed by maize and then beans, becoming part of the Three Sisters agricultural system of companion planting. All three crops have been frequently depicted in the art work of the native peoples of the Americas for at least 2,000 years. For example, squashes are represented frequently in Moche ceramics.
The English word "squash" derives from askutasquash (a green thing eaten raw), a word from the Narragansett language, which was documented by Roger Williams, the founder of Rhode Island, in his 1643 publication A Key Into the Language of America. Similar words for squash exist in related languages of the Algonquian family.
Cucurbita began to spread to other parts of the world after Christopher Columbus's arrival in the New World in 1492. Until 1992, the earliest known depictions of this genus in Europe was of Cucurbita pepo in De Historia Stirpium Commentarii Insignes in 1542 by Leonhart Fuchs, a German botanist. In 1992, two paintings, one of C. pepo and one of C. maxima, were found in a festoon at Villa Farnesina in Rome. These were painted between 1515 and 1518. In 2001 depictions of this genus were found in Grandes Heures of Anne of Brittany (Les Grandes Heures d'Anne de Bretagne), a French devotional book printed between 1503 and 1508. This book contains an illustration known as Quegourdes de turquie, which was identified by cucurbit specialists as C. pepo subsp. texana in 2006.
The full phylogeny of this genus is unknown, and research is ongoing in 2014. The following cladogram of Cucurbita phylogeny is based upon a 2002 study based on mitochondrial DNA by Sanjur et al.
Cucurbita was formally described in 1753 in Linnaeus's Species Plantarum, which established modern botanical nomenclature. Cucurbita pepo is the type species of the genus. The Cucurbita digitata, C. foetidissima, C. galeotti, and C. pedatifolia species groups are xerophytes, arid zone perennials with storage roots; the remainder, including the five domesticated species, are all mesophytic annuals or short-life perennials with no storage roots. The five domesticated species are mostly isolated from each other by sterility barriers and have different physiological characteristics. Some cross pollinations can occur: C. pepo with C. argyrosperma and C. moschata; and C. maxima with C. moschata. Cross pollination does occur readily within the family Cucurbitaceae. The buffalo gourd (C. foetidissima), which does not taste good, has been used as an intermediary as it can cross breed with all the common Cucurbita.
Various taxonomic treatments have been proposed for Cucurbita, ranging from 13–30 species. In 1990, Michael Nee classified them into the following 13 species groups (27 species total), listed by group and alphabetically, with geographic origin:
The taxonomy by Nee closely matches the species groupings reported in a pair of studies by a botanical team led by Rhodes and Bemis in 1968 and 1970 based on statistical groupings of several phenotypic traits of 21 species. Seeds for studying additional species members were not available. Sixteen of the 21 species were grouped into five clusters with the remaining five being classified separately:
Of the five domesticated species, four of them: Cucurbita argyrosperma, C. ficifolia, C. moschata, and C. pepo originated and were domesticated in Mesoamerica; whereas in the case of C. maxima this occurred in South America. The exact location of origin of C. ficifolia and C. moschata is less certain.
Within C. pepo, the pumpkins, scallops, and possibly crooknecks are ancient and were domesticated separately. The domesticated forms of C. pepo have larger fruits and larger yet fewer seeds. In a 1989 study on the origins and development of C. pepo, Paris suggested that the original wild specimen was a small round fruit and that the modern pumpkin is its direct descendant. He suggested that the crookneck, ornamental gourd, and scallop are early variants and that the acorn is a cross between the scallop and pumpkin.
Cucurbita argyrosperma is not as widespread as the other species but is found from Mexico to Nicaragua. It has large seeds that are high in oil and protein and was likely bred for its seeds. Its flesh is of poorer quality than that of C. moschata and C. pepo. It is found from sea level to as high as 1,800 meters (5,900 ft) in dry areas or areas with a defined rainy season. Seeds are sown in May–June and fruit harvested from October–December.
Cucurbita ficifolia and C. moschata were originally thought to be Asiatic in origin, but this has been disproven. The origin of C. ficifolia is Latin America, most likely southern Mexico, Central America, or the Andes. It grows at altitudes from 1,000 meters (3,300 ft) to 3,000 meters (9,800 ft) in areas with heavy rainfall. It does not hybridize well with the other cultivated species as it has significantly different enzymes and chromosomes.
Cucurbita maxima originated in South America over 4,000 years ago, most likely Argentina and Uruguay. They are sensitive to frost, prefer sunlight, and thrive in soil with a pH of 6.0 to 7.0. It did not start to spread into North America until after the arrival of Columbus. By the 16th century varieties were in use by native peoples of the United States. Groups of C. maxima include Triloba, Zapallito, Zipinka, Banana, Delicious, Hubbard, Marrow (C. maxima Marrow), Show, and Turban.
Cucurbita moschata is native to Latin America but the precise location of origin is uncertain. It has been present in Mexico, Belize, Guatemala, and Peru for 4,000–6,000 years and has spread to Bolivia, Ecuador, Panama, Puerto Rico, and Venezuela. This species is closely related to C. argyrosperma. A variety known as the Seminole Pumpkin has been cultivated in Florida since before the arrival of Columbus. Its leaves are 20 to 30 centimeters (7.9 to 11.8 in) wide. It generally grows at low altitudes in hot climates with heavy rainfall, but some varieties have been found above 2,200 meters (7,200 ft). Groups of C. moschata include: Cheese, Crookneck (C. moschata), and Bell.
Cucurbita pepo is one of the oldest, if not the oldest domesticated species with the oldest known locations being Oaxaca, Mexico, 8,000–10,000 years ago and Ocampo, Tamaulipas, Mexico, about 7,000 years ago. It is known to have appeared in Missouri, United States, at least 4,000 years ago. Debates about the origin of C. pepo have been going on since at least 1857. There have traditionally been two opposing theories about its origin: 1) that it is a direct descendant of C. texana and 2) that C. texana is merely feral C. pepo. A more recent theory by botanist Andres in 1987 is that it is a descendant of C. fraterna and hybridized with C. texana; resulting in two distinct domestication events in two different areas: one in Mexico and one in the eastern United States, with C. fraterna and C. texana, respectively, as the ancestral species. C. pepo may have appeared in the Old World prior to moving from Mexico into South America. It is found from sea level to slightly above 2,000 meters (6,600 ft). Leaves have 3–5 lobes and are 20–35 cm wide. All the subspecies, varieties, and cultivars are conspecific and interfertile. In 1986 botanist Paris proposed a taxonomy of C. pepo consisting of eight edible groups based on their basic shape. All but a few C. pepo can be included in these groups. These eight edible cultivated varieties of C. pepo vary widely in shape and color, and one non-edible cultivated variety:
|Cultivar group||Botanical name||Image||Description|
|Acorn||C. pepo var. turbinata||winter squash, both a shrubby and creeping plant, obovoid or conical shape, pointed at the apex and with longitudinal grooves, thus resembling a spinning top, ex: Acorn squash|
|Cocozzelle||C. pepo var. Ionga||summer squash, long round slender fruit that is slightly bulbous at the apex, similar to fastigata, ex: Cocozelle von tripolis|
|Crookneck||C. pepo var. torticollia (also torticollis)||summer squash, shrubby plant, with yellow, golden, or white fruit which is long and curved at the end and generally has a verrucose (wart-covered) rind, ex: Yellow crookneck squash|
|Pumpkin||C. pepo var. pepo||winter squash, creeping plant, round, oblate, or oval shape and round or flat on the ends, ex: Pumpkin; includes C. pepo subsp. pepo var. styriaca, used for Styrian pumpkin seed oil|
|Scallop||C. pepo var. clypeata; called C. melopepo by Linnaeus||summer squash, prefers half-shrubby habitat, flattened or slightly discoidal shape, with undulations or equatorial edges, ex: Pattypan squash|
|Straightneck||C. pepo var. recticollis||summer squash, shrubby plant, with yellow or golden fruit and verrucose rind, similar to var. torticollia but a stem end that narrows, ex: Yellow summer squash|
|Vegetable marrow||C. pepo var. fastigata||summer and winter squashes, creeper traits and a semi-shrub, cream to dark green color, short round fruit with a slightly broad apex, ex: Spaghetti squash (a winter variety)|
|Zucchini||C. pepo var. cylindrica||summer squash, presently the most common group of cultivars, origin is recent (19th century), semi-shrubby, cylindrical fruit with a mostly consistent diameter, similar to fastigata, ex: Zucchini|
|Ornamental gourds||C. pepo var. ovifera||non-edible, field pumpkins closely related to C. texana, vine habitat, thin stems, small leaves, three sub-groups: C. pepo var. ovifera (egg-shaped, pear-shaped), C. pepo var. aurantia (orange color), and C. pepo var. verrucosa (round warty gourds), ornamental gourds found in Texas and called var. texana and ornamental gourds found outside of Texas (Illinois, Missouri, Arkansas, Oklahoma, and Louisiana) are called var. ozarkana.|
The species of Cucurbita are prepared and consumed in many ways. While the skins are often bitter, the fruits and seeds of cultivated varieties are quite edible by humans with little or no preparation. The seeds and fruits of most varieties can be stored for long periods of time. In addition, the young leaves, young shoot tips, and flowers can be consumed. The Cucurbitaceae family has the largest number of different species used as human food of any plant family. Cucurbita is one of the most important of those, either for their fruit or the seeds within. The winter varieties have thick, inedible skins, and so store well. They have a sweet taste. In contrast, summer squash have a thin, edible skin. The seeds of both types can be ground into a flour or meal, roasted, eaten raw, made into pumpkin seed oil, or otherwise prepared. Buffalo gourd oil is made from Cucurbita foetidissima. By the time of European contact Cucurbita had long been a major food source for the native peoples of the Americas. They became an important food for the European settlers, including the Pilgrims, for whom they were a major part of the first Thanksgiving. The large red-orange squashes often seen at Halloween in the United States are C. maxima, but not to be confused with the orange type used for jack-o-lanterns, which are C. pepo. Commercially made pumpkin pie mix is most often made from varieties of C. moschata; 'Libby's Select' uses the Select Dickinson Pumpkin variety of C. moschata for its canned pumpkins. Other foods that can be made using members of this genus include biscuits, bread, cheesecake, desserts, donuts, granola, ice cream, lasagna dishes, pancakes, pudding, pumpkin butter, salads, soups, and stuffing. The species that are xerophytes are proving useful in the search for nutritious foods that grow well in arid regions.
Cucurbita is used in cosmetics for dry and sensitive skin and in treating schistosomiasis. The flesh of Cucurbita argyrosperma is used for treating burns and skin conditions while its seeds are treated with water and used as an anesthetic and to promote lactation in nursing women. C. ficifolia is used to make flavorings for soft and mildly alcoholic drinks, and high doses of C. ficifolia have been shown to be successful in reducing blood sugar levels. The fruits of some species, such as C. foetidissima, are used as soaps and detergents. Cucurbita fruits are an important source for humans of carotenoids, vitamin A, and rhodopsin, all of which are important to good visual acuity. Cucurbitin is an amino acid and a carboxypyrrolidine found in Cucurbita seeds that can eliminate parasitic worms.
|Nutritional value per 100 g (3.5 oz)|
|Energy||69 kJ (16 kcal)|
|Dietary fiber||1.1 g|
|Vitamin A equiv.|
|Percentages are roughly approximated using US recommendations for adults.|
Source: USDA Nutrient Database
Cucurbita have phytochemical constituents such as alkaloids, flavonoids, and palmitic, plus oleic and linoleic acids. Pumpkins have anti-diabetic, antioxidant, anticarcinogen, and anti-inflammatory pharmacological properties include. Pumpkins and pumpkin seeds have high levels of crude protein, calcium, iron, potassium, phosphorus, magnesium, zinc, and beta-carotene. Squashes are good sources of vitamin A, vitamin C, potassium, dietary fiber, niacin, folic acid, and iron. They are free of fat and cholesterol.
Cucurmosin is a ribosome inactivating protein found in the sarcocarp (flesh) and seed of Cucurbita, notably Cucurbita moschata. Cucurmosin is more toxic to cancer cells than healthy cells.
Cucurbitacin is a plant steroid poisonous to mammals found in wild Cucurbita in quantities sufficient to discourage herbivores. It has been bred out of cultivated varieties. It has a bitter taste and ingesting too much can cause stomach cramps, diarrhea and even collapse. While the process of domestication has largely removed the bitterness from the cultivated varieties, there are occasional reports of cucurbitacin getting into the human food supply and causing illnesses. This is what makes wild Cucurbita and most ornamental gourds, with the exception of an occasional C. fraterna and C. sororia, bitter to taste.
Cucurbita species are used as food plants by the larvae of some Lepidoptera species, including Cabbage Moths, Hypercompe indecisa, and Turnip Moths. Cucurbita can be susceptible to the pest Bemisia argentifolii (silverleaf whitefly) as well as aphids (Aphididae), cucumber beetles (Acalymma vittatum and Diabrotica undecimpunctata howardi), squash bug (Anasa tristis), the squash vine borer (Melittia cucurbitae), and the twospotted spidermite (Tetranychus urticae). The squash bug causes major damage to plants because of its very toxic saliva. Cucurbits are susceptible to diseases such as bacterial wilt (Erwinia tracheiphila), anthracnose (Colletotrichum spp.), fusarium wilt (Fusarium spp.), phytophthora blight (Phytophthora spp. water molds), and powdery mildew (Erysiphe spp.). Defensive responses to viral, fungal, and bacterial leaf pathogens do not involve cucurbitacin.
Species in the genus Cucurbita are susceptible to some types of mosaic virus including: Cucumber mosaic virus (CMV), Papaya ringspot virus-cucurbit strain (PRSV), Squash mosaic virus (SqMV), Tobacco ringspot virus (TRSV), Watermelon mosaic virus (WMV), and Zucchini yellow mosaic virus (ZYMV). PRSV is the only one of these viruses that does not affect all cucurbits, which is the family Cucurbitaceae. SqMV and CMV are the most common viruses among cucurbits. Symptoms of these viruses show a high degree of similarity and laboratory investigation is often needed to differentiate which one is affecting plants.
Squashes are primarily grown for the fresh food market. The Food and Agriculture Organization of the United Nations (FAO) reported that the ranking of the top five squash-producing countries was stable from 2005–2009. Those countries are: China, India, Russia, the United States, and Egypt. By 2012, Iran had moved into the 5th slot, with Egypt falling to 6th. The top 10 countries in terms of metric tons of squashes produced are:
|Top 10 total||15,663,449|
The only other countries that rank in the top 20 where squashes are native are Cuba, which ranks 14th with 347,082 metric tons, and Argentina, which ranks 17th, with 326,900 metric tons. In addition to being the 4th largest producer of squashes in the world, the United States is the world's largest importer of squashes, importing 271,614 metric tons in 2011, 95% of that from Mexico. Within the United States, the states producing the largest amounts are: Florida, New York, California, and North Carolina.
This is how Cucurbita compares to a couple of other major Cucurbitaceae crops in terms of crop tonnage harvested:
|Top 10 total||49,075,599|
|Top 10 total||73,490,835|
|External identifiers for Cucurbita|
|Encyclopedia of Life||38266|
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