Species of flowering plant that yields varieties of squash and pumpkin
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Cucurbita pepo is a cultivated plant of the genus "Cucurbita". It yields varieties of winter squash and pumpkin, but the most widespread varieties belong to the subspecies "Cucurbita pepo" subsp. "pepo", called summer squash.
It has been domesticated in the Americas for thousands of years. Some authors maintain that "C. pepo" is derived from "C. texana", while others suggest that "C. texana" is merely feral "C. pepo". They have a wide variety of uses, especially as a food source and for medical conditions. "C. pepo" seems more closely related to "C. fraterna", though disagreements exist about the exact nature of that connection, too.
It is a host species for the melonworm moth, the squash vine borer, and the pickleworm. They are also the preferred pollen for squash bees.
Description.
Due to their varied genetic background, members of "C. pepo" vary widely in appearance, primarily in regards to their fruits. The plants are typically high and wide, with yellow flowers. Within "C. pepo", the pumpkins, scallops, and possibly crooknecks are ancient and were domesticated separately. The domesticated species have larger fruits and larger yet fewer seeds. Parthenocarpy is known to occur in certain cultivars of "C. pepo".
The leaves have three to five lobes and are wide. All the subspecies, varieties, and cultivars are conspecific and interfertile.
Taxonomy.
Origin and history.
"C. pepo" is one of the oldest, if not the oldest domesticated species. The oldest known locations are in southern Mexico in Oaxaca 8,000–10,000 years ago and Ocampo, Tamaulipas, Mexico about 7,000 years ago. 
Before the arrival of Europeans, "C. pepo", along with "C. moschata", had been carried over all parts of North America where they could be grown. The ancient territory of "C. pepo" extended north into Texas and up the Greater Mississippi River Valley into Illinois and east to Florida, and possibly even to Maine. It is one of several plants cultivated in prehistoric North America as part of the Eastern Agricultural Complex. It is known to have appeared in Missouri at least 4,000 years ago. Some varieties grow in arid regions and some in moist regions. Many of these peoples, particularly in the west, still grow a diversity of hardy squashes and pumpkins not to be found in commercial markets. Still, neither "C. pepo" nor "C. moschata" had been carried into South America as had beans, which originated in the same general region.
Debates about the origin of "C. pepo" have been going on since at least 1857. Recent biosystematic investigations indicate two distinct domestication events in two different areas: one in Mexico and one in the eastern United States, with "C. pepo subsp. fraterna" and "C. pepo subsp. texana", respectively, as the predominant ancestral species from a phylogenetic perspective.
Subdivision.
The morphological differences within the species "C. pepo" are so vast that its various subspecies and cultivars have been misidentified as totally separate species. These vast differences are rooted in its widespread geographic distribution. 
Several taxa have been proposed, but as of 2012 none has been universally accepted. In 2002, the taxa conventions proposed by Decker-Walters were:
A 2003 study recognized three subspecies:
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" cultivars can be included in these groups. These eight edible cultivated varieties of "C. pepo" vary widely in shape and color, and one inedible cultivated variety:
Random amplified polymorphic DNA has proven useful in sorting out the relationships of the "C. pepo" species, varieties, and cultivars, showing that few, if any, modern cultivars have their origins with "C. texana". They are associated with "C. fraterna" or a still-unknown ancestral specimen in southern Mexico.
It has been proposed that the domesticated forms of "C. pepo" are a compilospecies of "C. pepo subsp. fraterna" and "C. pepo subsp. texana". A 1989 study on the origins and development of "C. pepo" suggested that the original wild specimen was a small round fruit and that the modern pumpkin is its direct descendant. This investigation proposed that the crookneck, ornamental gourd, and scallop are early variants, and that the acorn is a cross between the scallop and pumpkin.
Based on genetic allele analysis, two distinct groups occur within domesticated "C. pepo": pumpkin, calabaza, criolla, and marrow squash are in one; and ornamental gourds, crookneck, acorn, scallop, and a few others in the second one. "C. pepo subsp. fraterna" is genetically closer to the first group and "C. pepo subsp. texana" is genetically closer to the second group.
Subspecies "fraterna".
This subspecies was formerly considered a separate species called "C. fraterna" by some authorities, but modern biosystematics has placed it as a subspecies of "C. pepo". The isozymes are similar between "Cucurbita pepo subsp. pepo", and all studied "C. fraterna" alleles are also found in "C. pepo subsp. pepo". It is native to Tamaulipas and Nuevo León, Mexico. This subspecies has not been domesticated. It is considered to be the progenitor and nearest relative of the domesticated subspecies "C. pepo subsp. pepo" which is found in the same areas as "C. pepo subsp. fraterna". It was first formally described by Liberty Hyde Bailey in 1943, in "Gentes Herbarum".
Unlike most wild "Cucurbita", some specimens of "C. fraterna" have been found without bitter fruit. Its usual habitat is dry upland scrub areas. It blooms in September and fruits ripen in December.
Subspecies "texana".
This subspecies was formerly considered a separate species "C. texana" by some authorities before being reclassified as a subspecies of "C. pepo". A common name is Texas gourd. This subspecies is mesophytic and native to Texas, primarily the southeastern region where it can be found in or near sandy riverbeds. It is found only in the wild. It is possibly a progenitor and close relative of the domesticated subspecies "Cucurbita pepo subsp. ovifera", though they are native to different areas. The "fraterna" subspecies is also closely related. It was first collected 1835 by J. L. Berlandier in southern Texas. It was formally described as "Tristemon texanus" by George Heinrich Adolf Scheele in 1848 and transferred to the genus "Cucurbita" by Asa Gray in 1850.
Distribution and habitat.
The species is found from sea level to slightly above .
Uses.
It is an ingredient in ""schumaakwe" cakes" and is used externally for rheumatism and swelling. A poultice of seeds and blossoms is applied to cactus scratches. Fresh squash is cut into spiral strips, folded into hanks and hung up to dry for winter use. The blossoms are cooked in grease and used as a delicacy in combination with other foods. Fresh squash, either whole or in pieces, is roasted in ashes and used for food. The gourds can be made into cups, ladles, and dippers and put to various uses. The gourds are also worn in phallic dances symbolizing fructification or made into ceremonial rattles. Gourds are also made into receptacles for storing precious articles.
References.
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