Deena S Decker-Walters & Terrence W Walters. Cambridge World History of Food. Editor: Kenneth F Kiple & Kriemhild Conee Ornelas. Volume 1. Cambridge, United Kingdom: Cambridge University Press, 2000.
Wild and domesticated members of the New World genus Cucurbita L. (Cucurbitaceae) are typically referred to as “gourds,””pumpkins,” and “squashes.”The mature fruit of wild plants, technically called a pepo, has gourdlike qualities like a tough rind and dry flesh. These same qualities have led to the term “ornamental gourds” for various cultivars of Cururbita pepo L. that are grown for their decorative but inedible fruits. However, the common name for the domesticated Cucurbita ficifolia Bouché is “fig-leaf gourd,” even though the fleshy fruits are cultivated for human consumption. Because another genus of the Cucurbitaceae, Lagenaria L., is considered the true gourd, it is preferable to refer to members of Cucurbita differentially, which leads us to the terms “pumpkin”and “squash.”
Pumpkin comes from the Old English word “pom-pion,” which is itself derived from the Greek pepon and the Latin pepothat together mean a large, ripe, round melon or gourd. Traditionally, “pumpkin” has been used to describe those cultivars of Cururbita argyrospermaHuber, Cururbita maxima Lam., Cururbita moschata (Lam.) Poir., and C. pepo that produce rotund mature fruits used in baking and for feeding livestock.
“Squash,” by contrast, is a term derived from the New England aboriginal word “askutasquash,” meaning vegetables eaten green. It was used during the seventeenth century to designate cultivars, usually of C. pepo, grown for their edible immature fruits, and by the nineteenth century, called “summer squashes.” “Winter squashes,” in contrast, are the mature fruits of C. argyrosperma, C. maxima, C. moschata, and C. pepo that store well and are not usually round; they are prepared as vegetables, baked into pies, or used as forage. Although “winter squashes” are supposed to differ from “pumpkins” in having a milder taste and flesh of a finer grain, the truth is that these culinary categories overlap, adding to the confusion in nomenclature. For the purposes of this discussion, the generic “squash” will refer to all wild and domesticated members of Cucurbita.
Squash Growers and Researchers
The story of squash is a story of Native Americans and New World archaeologists, gold-seeking explorers and European colonizers, herbalists and horticulturists, breeders and botanists. Squashes fascinate us all, but none more than the people who have dedicated their careers to squash research. Such research, as we know it, was under way in Europe by the 1800s. Intrigued by the diversity of fruits illustrated in the herbals of the sixteenth and seventeenth centuries (see Whitaker 1947; Eisendrath 1962; Paris 1989), the French horticulturist Charles Naudin (1856) took great pleasure in describing, breeding, and classifying these newcomers to the Old World. By the twentieth century, comprehensive breeding programs were well established in Europe, North America, and Asia. In an attempt to keep pace with the burgeoning of new strains, William Tapley, Walter Enzie, and Glen Van Eseltine (1937) combed the horticultural literature to provide the most detailed descriptions ever of 132 cultivars.
From Russia, organized plant-collecting expeditions were launched to search Middle and South America, eastern Africa, India, and Asia Minor for new landraces. These explorations provided the bases for new classifications (e.g., Bukasov 1930; Pangalo 1930; Zhiteneva 1930; Filov 1966). Other scientists also contributed to the systematics of squash, with Igor Grebenščikov (1955, 1958, 1969) updating an earlier (Alefeld 1866) classification of infraspecific varieties. The Americans E. F. Castetter and A.T. Erwin took a different approach, placing cultivars into horticultural groups as opposed to botanical classes (Castetter 1925; Castetter and Erwin 1927).
During the middle of the twentieth century, archaeological discoveries of ancient squash in the New World (Whitaker and Bird 1949;Whitaker, Cutler, and MacNeish 1957; Cutler and Whitaker 1961; Whitaker and Cutler 1971) provided an added perspective on the history and evolution of these species. In recent decades, some of the most ancient and most accurately dated and identified squash remains (e.g., Kay, King, and Robinson 1980; Conrad et al. 1984; Simmons 1986; Decker and Newsom 1988) have served to highlight the importance of C. pepo in the origins and character of North American horticulture (Heiser 1979; Minnis 1992; Smith 1992). Moreover, archaeological studies in South America have also blossomed recently (see Pearsall 1992 and refs. therein), giving us more detailed histories of C. ficifolia and C. maxima.
Domesticated squashes, with their diversity in fruit characteristics, have long been of interest to horticultural geneticists (e.g., Sinnott 1922; Shifriss 1955; Wall 1961; Robinson et al. 1976). Liberty Hyde Bailey, who explored North America in search of wild species, spent countless hours in his gardens performing breeding and inheritance experiments and making observations on the domesticates (Bailey 1902, 1929, 1937, 1943, 1948).
Thomas Whitaker, a prolific researcher with the United States Department of Agriculture, has been the closest human ally of the cucurbits. He examined relationships among wild and domesticated squashes using all available sources of data, including archaeo-logical remains, hybridization experiments, anatomical and morphological studies, and various genetic analysis (e.g., Whitaker 1931, 1951, 1956, 1968; Whitaker and Bohn 1950; Cutler and Whitaker 1956; Whitaker and Bemis 1964; Whitaker and Cutler 1965). Other devoted squash enthusiasts of the twentieth century include Hugh Cutler and W. P. Bemis, who often worked and published with Whitaker.
In recent years, individual domesticated squash species have been scrutinized to determine their evolutionary histories from wild progenitor(s) through domestication to diversification and geographic spread. As an additional source of phylogenetic data, isozyme analyses aided Deena Decker-Walters and Hugh Wilson in their examination of C. pepo(Decker 1985, 1988; Decker and Wilson 1987), Laura Merrick (1990) in the study of C. argyrosperma, and Thomas Andres (1990) in his evaluation of C. ficifolia. Similar modern and detailed research is lacking for C. maxima and C. moschata.
Two very different but nonetheless comprehensive books have been written on members of the Cucurbitaceae. One by Whitaker and Glen Davis (1962) reviews past research to provide the most up-to-date (at that time) coverage on the description, history, genetics, physiology, culture, uses, and chemistry of economically important cucurbits, including squashes.The other, Biology and Utilization of the Cucurbitaceae, edited by David Bates, Richard Robinson, and Charles Jeffrey (1990), includes 36 distinct articles written by leading experts of the day and covering the systematics, evolution, morphology, sex expression, utilization, crop breeding,and culture of squashes and other cucurbits.
Plant and Fruit Descriptions
Five domesticated and about 20 wild squash species grow in dry or somewhat humid regions of the tropics, subtropics, and mild temperate zones.Their native turf ranges from the central United States south to central Argentina, with species diversity being greatest in Mexico.The herbaceous vines are not frost-tolerant. However, some of the xerophytic perennials have large storage roots that can survive a snowy winter. Among the mesophytic annuals, which include the domesticates, quick germination, early flowering, and rapid growth have enabled some to adapt to the more extreme latitudes.
Squash plants are monoecious, tendriliferous vines with leaves ranging from entire to lobed and large, yellow to yellow-orange, campanulate flowers. The ephemeral blossoms, opening only once in the morning, are pollinated primarily by specially adapted solitary bees. The inferior ovary of the female flower develops into a gourdlike fruit called a pepo. Pepos of wild plants are usually round with a tough rind and bitter flesh, whereas domesticated fruits generally lack bitterness and are multifarious in their characteristics.
Although primarily outcrossers, individual plants are self-compatible. Hybridization can also occur between some species. In fact, all squash species have 20 pairs of chromosomes and are incompletely isolated from one another by genetic barriers.This ability to cross species boundaries has been important for plant breeders, allowing them to transfer genes controlling favorable qualities from one species to another. In this way, resistance to the cucumber mosaic virus was transferred from a distantly related wild species to cultivated C. pepo, using C. moschata as the intermediary.
Archaeological remains, hybridization studies, and genetic data suggest that the domesticated species were independently selected from genetically distinct wild progenitors. In spite of their separate origins, C. argyrospermaand C. moschata are closely related. In fact, C. argyrosperma was not recognized as a distinct species until the Russian geneticist K. I. Pangalo (1930) described it as Cucurbita mixta Pang. following extensive collecting expeditions to Mexico and Central America. Even so, it can be difficult to correctly identify some plants and fruits. Generally, fruits of C. argyrosperma have enlarged corky peduncles, whereas those of C. moschata are hard and thin but distinctly flared at the fruit end. Also, the green and/or white fruits of C. argyrosperma, which sometimes mature to yellow, rarely display the orange rind coloring that is common among cultivars of C. moschata. Foliaceous sepals are largely unique to but not ubiquitous in C. moschata. Leaf mottling is more common in C.moschata and leaf lobes deeper in C.argyrosperma.
Both species have large flowers with long slender androecia, relatively soft pubescence on the foliage, and distinctly colored seed margins. Among the domesticated species, these squashes best survive the hot, humid, low-elevation (usually under 1,500 meters [m] above sea level) climes of the mid-latitudes, often failing to flower when daylengths are too long. But relative to the wide pre-Columbian distribution and diversity in C. moschata, C. argyrosperma has remained limited in its geography and genetic variability.
There are three domesticated varieties of C. argyrosperma subspecies (ssp.) argyrosperma—variety (var.) argyrosperma, var. callicarpa Merrick and Bates, var. stenosperma (Pang.) Merrick and Bates—and a weedy variety, var. palmeri (Bailey) Merrick and Bates. Most of the diversity in this squash can still be found in the endemic landraces of the southwestern United States, Mexico, and Central America.The moderately sized, unfurrowed fruits range from globose to pyriform to long-necked; in the latter, the necks may be straight or curved. Rinds are generally decorated with splotchy, irregular green and white stripes, though in var. callicarpa, solid white or green fruits are common and the green coloration is often lacy. Commercial cultivars are few, as culinary quality of the pale yellow to orange flesh is relatively poor in this species. Most of the cultivars and landraces in commercial trade today represent var. callicarpa.
Fruits of C. moschata, weighing up to 15 kilograms (kg) apiece, range from squatty to round to turbinate, pyriform, or oblong to necked. Furrows, sometimes deep, are common and wartiness occasional. The rinds are solid, splotchy, or striped in dark to light greens, whites, creams, yellows, and oranges. Fruit flesh is usually deep yellow or orange.
In North America, cultivars of C. moschata have been placed into three horticultural groups—”cheese pumpkins,” “crooknecks,” and “bell squashes.” However, these groups do not satisfactorily accommodate the diversity of landraces that have evolved in tropical regions around the globe. For example, C. moschata is widely cultivated in Asia, and several unusual cultivars with names like ‘Chirimen’, ‘Kikuza’, ‘Saikyo’, and ‘Yokohama’ originated in Japan. Fruit characteristics resembling those of C. argyrosperma ssp. argyrosperma indicate that the Japanese cultivars may have arisen from interspecific crossings. Genetic diversity in some northwestern Mexican landraces of C. moschata also may be the result of introgression from wild and/or cultivated C. argyrosperma.
A. I. Filov (1966) expanded earlier classifications of C. moschata to include over 20 varieties in several geographical subspecies. Unfortunately, modern systematic and genetic studies that would confirm the natural relationships among cultivars within and among regions are lacking. Nevertheless, these geographical subspecies do reveal centers of diversification that include Colombia, where the seeds are darker and the plants and fruits small; Mexico, Central America, and the West Indies, where landraces are genetically variable and fruits of many shapes and colors can be found in a single field; Florida, which is home to the small-fruited, aboriginal ‘Seminole Pumpkin’; Japan with its warty and wrinkled fruits; India, where large soft-skinned fruits abound; and Asia Minor, where fruits again are variable but long barbell-shaped pepos predominate.
Although C. moschata is the most widely cultivated squash in underdeveloped tropical countries, as with C. argyrosperma, relatively few cultivars have entered the commercial trade of Europe and North America. “Cheese pumpkins” and “crook-necks” were popular in nineteenth-century New England.Today, only various selections from the “bell squashes” are commonly sold by seed suppliers.
Cucurbita pepo is characterized by uniformly colored tan seeds, lobed leaves with prickly pubescence, hard roughly angled peduncles, and short, thick, conical androecia. Flowers range from small to large, though they are rarely as grand as those of C. argyrosperma ssp. argyrosperma. Genetic diversity, expressed in the plethora of differing fruit forms, is greatest in this squash. Orange flesh color is not as common in C. pepo as it is in C. maxima or C. moschata.
Cucurbita pepo appears to have shared a Mexican or Central American ancestor with C. argyrosperma and C. moschata. From those origins, wild populations—ssp. ovifera (L.) Decker var. ozarkana Decker-Walters, ssp. oviferavar. texana (Scheele) Decker, ssp. fraterna (Bailey) Andres, ssp. pepo—spread over North America before at least two domestications of C. pepo took place to produce ssp. ovifera var. ovifera (L.) Decker and cultivars of ssp. pepo. BecauseC. pepo can tolerate cooler temperatures than can C. argyrosperma and C. moschata, this squash flourishes at more extreme latitudes and higher elevations (1,600 to 2,100 m above sea level) to the delight of farmers from southern Canada to the highlands of Central America. Some wild populations and cultivars are well adapted to the northern United States, with seeds that are quick to germinate and early flowering that is responsive to changes in daylength.
Encompassing many hundreds of cultivars, six horticultural groups of C. pepo were recognized during the twentieth century. “Acorn squashes,” “crooknecks,” “scallop squashes,” and most “ornamental gourds” belong to ssp. ovifera var. ovifera. Horticulturists have traditionally classified all small, hard-shelled, bitter fruits grown for autumn decorations as ornamental gourds. However, this classification does not reflect the fact that these gourds have various genealogies that include wild populations of ssp. ovifera, ssp. pepo, and probably ssp. fraterna. Pumpkins, such as those grown in temperate to tropical gardens around the globe, and marrows belong to ssp. pepo. The former, like acorn squashes, are eaten when mature, whereas the latter, like the crooknecks and scallop squashes, are summer squashes picked during the first week of fruit development. Bushy plants with relatively short internodes have been developed for most of the summer squashes as well as for some of the acorn squashes.
Cucurbita maxima is distantly related to the trio just discussed.This squash, whose origins are in South America, exhibits closer genetic affinities to other wild South American species. Like C. pepo, some cultivars and landraces of C. maxima can tolerate the relatively cool temperatures of the highlands (up to 2,000 m above sea level).Today, this species is grown in tropical to temperate regions around the globe, particularly in South America, southeastern Asia, India, and Africa.
Cucurbita maxima is distinguished by its soft round stems, entire or shallowly lobed unpointed leaves, and spongy, enlarged, terete peduncles. Compared to the other domesticates, the white or brown seeds of this squash are thick, particularly in relationship to their margins.The androecium is short, thick, and columnar.The yellow or orange fruit flesh is fine-grained and of the highest quality (tasty and relatively rich in vitamins) among all squashes. Fruits are quite variable in size, shape, and coloration, with the latter including many shades of gray, green, blue, pink, red, and orange in striped, mottled, or blotchy patterns.
A distinct fruit form characterizes cultivars classified as “turban squashes.” The immature ovary protrudes upward from the receptacle, swelling into a turban-shaped fruit with a crown (the part of the fruit not enveloped by the receptacle) upon maturity. Table II.C.8.4 lists some turban squash cultivars and describes five other traditionally recognized horticultural groups—”banana squashes,” “delicious squashes,” “hubbard squashes,” “marrows,” and “show pumpkins.”
Over 50 cultivars of C. maxima had been commercially traded by the early twentieth century; today, this number has reached over 200. Not all landraces and cultivars can be assigned to the horticultural groups in Table II.C.8.4. Some cultivars, such as the warty ‘Victor’, were derived from hybridizations between horticultural groups. Local landraces that never entered into, or played only minor roles in, American and European commercial trade often have fruit traits that do not match those characterizing the groups. And although several varieties of C. maxima have been proposed over the years, as of yet no one has performed an intensive systematic study of this species to clarify evolutionary relationships among cultivars and groups of cultivars.
Cucurbita ficifolia is not closely related to the other domesticated squashes or to any known wild populations. Distinguishing characteristics include relatively wide, minutely pitted, solid-colored seeds, ranging from tan to black; white, coarsely fibrous flesh; an androecium shaped like that of C. maxima but with hairs on the filaments; and rounded lobed leaves. Genetic uniformity in this species is evidenced by the lack of variation in fruit characteristics.The large oblong fruits, measuring 15 to 50 centimeters (cm) long, exhibit only three basic rind coloration patterns: solid white, a reticulated pattern of green on white that may include white stripes, and mostly green with or without white stripes. No distinct landraces or cultivars of C. ficifolia have been recognized.
In Latin America today, this cool-tolerant, short-day squash is grown for food in small, high-altitude (1,000 to 2,800 m above sea level) gardens from northern Mexico through Central America and the Andes to central Chile. Usually the mature fruits are candied, but the seeds and immature fruits are eaten as well. Cucurbita ficifolia is also cultivated as an ornamental in Europe and the United States and for forage in underdeveloped countries of the Old World.
The Evolution and History of Squashes
The five domesticated squash species were brought under cultivation 5,000 to 15,000 years ago. Native Americans transformed the small green and white gourdlike pepos of wild plants into a cornucopia of colorful and shapely pumpkins and squashes. But long before they were domesticated, wild squash plants made their presence known to human populations. These fast-growing, tenacious vines are prolific opportunists, boldly invading disturbed sites of natural or human origin. Initial human interest in wild squash may have manifested itself in the use of the tough fruit rinds for containers. Additionally, the seeds are a tasty and nutritious source of food. The flesh of wild pepos is too bitter to eat raw.Toxic oxygenated tetracyclic triterpenes, called cucurbitacins, permeate the leaves, roots, and fruits as deterrents to herbivory. Nevertheless, the frequency of immature peduncles among archaeological remains suggests that the young tender fruits were consumed, probably after leaching out the cucurbitacins through multiple boilings.
The development of nonbitter pepos came about as a result of domestication. Indiscriminate harvesting of fruits from wild or tolerated weedy vines eventually led to the planting of seeds from selected genetic strains. In the process of selecting for larger fruits for containers or larger seeds for consumption, thicker, nonbitter, and less fibrous flesh was discovered and selected for as well. Other changes included the loss of seed dormancy, softer and more colorful fruit rinds, adaptation to shorter growing seasons, and generally larger plant parts. In this way, squash became a major component of diets for the ancient farmers of the New World.
Squash domestication took place at least five times to yield the cultivated members of C. argyrosperma, C. ficifolia, C. maxima, C. moschata, and C. pepo. These domestications involved genetically distinct wild populations and at least three different cultural groups inhabiting the eastern United States, Middle America, and South America. A discussion of the evolution of these cultivated squashes along with their history and spread follows.
Cultivars of C. argyrosperma ssp. argyrosperma are genetically similar to wild populations of C. argyrosperma ssp.sororia, a native of low-elevation, mostly coastal habitats in Mexico and Central America. Sufficient evidence exists to support the theory that ssp. sororia gave rise to domesticated ssp. argyrosperma. Domestication probably took place in southern Mexico, where the earliest remains of ssp. argyrosperma date around 5000 B.C. Most of these archaeological specimens belong to var. stenosperma; landraces of this variety are still grown in southern Mexico today. With a current distribution ranging from northeastern Mexico south to the Yucatan and into Central America, var. argyrosperma is the most widespread variety of ssp. argyrosperma. Remains of var. argyrosperma first appear in the archaeological record in northeastern Mexico at about A.D. 200. A little later (c. A.D. 400), var. callicarpa shows up at archaeological sites in the southwestern United States. The earliest pre-Columbian evidence of C. argyrosperma in eastern North America is fifteenth-century remains from northwestern Arkansas. Although the three varieties of ssp. argyrospermacould have been selected separately from wild populations of ssp. sororia, Merrick’s (1990) interpretation of the morphological evidence suggests that var. stenosperma and var. callicarpa evolved from southern and northern landraces of var. argyrosperma, respectively.
The fourth and final variety of spp. argyrosperma, var. palmeri, is weedy, possessing a mixture of characteristics otherwise representing wild spp. sororia and cultivated var. callicarpa. It grows unaided in disturbed areas, including cultivated fields, in northwestern Mexico beyond the range of ssp. sororia. Cucurbita argyrosperma ssp. argyrospermavar. palmeri may represent escapes of var. callicarpa that have persisted in the wild by gaining through mutation and/or hybridization with ssp. sororia those characteristics (such as bitter fruits) that are necessary for independent survival.
Current uses of wild and weedy fruits in Mexico include eating the seeds, using seeds and the bitter flesh medicinally, washing clothes with the saponin-rich flesh, and fashioning containers from the dried rinds. Although the antiquity of these uses is uncertain, selection for edible seeds has remained the dominant theme in cultivation. In southern Mexico and Guatemala, var. argyrosperma and var. stenosperma are grown for their large edible seeds, with the fruit flesh serving as forage. In southern Central America, indigenous cultures have produced landraces that yield a necked fruit eaten as a vegetable while immature and tender. Selection pressures in northern Mexico have created several landraces of var. argyrosperma and var. callicarpa; some produce mature pepos with quality flesh for human consumption as well as edible seeds, whereas others are grown for their immature fruits. At twelfth- and thirteenth-century sites in southern Utah, fruits of var. callicarpa were employed as containers, a use that persists among some tribes of the Southwest today.The greatest diversity of fruits in the species, represented primarily by var. callicarpa, occurs in northwestern Mexico and the southwestern United States
Relative to the post-Columbian changes incurred by other squashes, the spread and further diversification of C. argyrosperma cultivars has been limited. A few commercial cultivars such as ‘Green Striped Cushaw’ were selected from North American stock and grown in New England soon after colonization.A similar type of squash was illustrated in European herbals of the sixteenth century, and additional types were developed in South America and Asia. As a result of the recent trend to identify, save, and distribute native landraces of New World crops, a large number of landraces of C. argyrosperma indigenous to North America have entered the U.S. commercial trade under such names as ‘Chompa’,’Green Hopi Squash’, ‘Mayo Arrote’,’Montezuma Giant’, and ‘Pepinas’.
The earliest archaeological remains indicative of domestication of C. moschata were discovered in southern Mexico (5000 B.C.) and in coastal Peru (3000 B.C.). Ancient Peruvian specimens differ from those of Mexico by having a warty rind and a pronounced fringe along the seed margins. Although Mexico appears to be the more ancient site of domestication, the Peruvian remains and the diversity of Colombian landraces point to South America as a secondary site of early diversification or an independent center of domestication. Unfortunately, wild progenitor populations have not yet been identified for this species. It is possible that they are extinct; however, a few tantalizing finds of wild squash in Bolivia suggest that South American populations of C. moschata may be awaiting rediscovery. Among wild squashes known today in Middle America, those of C. argyrosperma ssp. sororia express the greatest genetic affinity to Mexican landraces of C. moschata.
Even though the centers of landrace diversity for C. moschata lie in Central America and northern South America, archaeological remains indicate that this species spread to northeastern Mexico by about 1400 B.C. and to the southwestern United States by A.D. 900. The spread of C. moschata to the Gulf coastal area and the Caribbean may have been facilitated by early Spanish explorers and missionaries; a distinctive Florida landrace called ‘Seminole Pumpkin’ is still grown by the Miccusokees of the Everglades. Among tribes of the Northern Plains, C. moschatawas definitely a post-Columbian introduction.
The crooknecks and cheese pumpkins, which probably have their origins in North America, were known to colonists and Europeans as early as the 1600s. Variations on the cheese pumpkin theme can be found in the large furrowed pumpkins of India and southeastern Asia. Additional diversification of C. moschata took place in Asia Minor, where various fruit types resemble the bell squashes, and in Japan, where selection was for heavily warted rinds. Completing its worldwide travels, this species was well established as a food crop in northern Africa by the nineteenth century.
The squash represented by the earliest archaeological remains is C. pepo. Its seeds and rinds of wild or cultivated material appear in Florida around 10,000 B.C., in southern Mexico around 8000 B.C., and in Illinois at around 5000 B.C. Enlarged seeds and peduncles as well as thicker fruit rinds suggest that this species was definitely under cultivation in southern and northeastern Mexico between 7500 and 5500 B.C. and in the Mississippi Valley between 3000 and 1000 B.C. Cultivation had spread from Mexico to the southwestern United States by around 1000 B.C., and by A.D. 1500, C. pepo landraces were being grown throughout the United States and Mexico.
Ancestral North Americans independently domesticated at least two genetically distinct and geographically disjunct subspecies of C. pepo to produce the two major lineages of cultivars known today. Although wild populations of ssp.pepo are currently unknown and possibly extinct, they were probably subjected to the selection pressures of the natives of southern Mexico, giving rise to the majority of Mexican and southwestern U.S. landraces, as well as to “pumpkin” and “marrow” cultivars of this species. As with C. argyrosperma and C. moschata, human selection with C. pepo landraces in southern Mexico focused on producing large seeds within a sturdy round fruit.
Today, wild populations of C. pepo range from northeastern Mexico (ssp. fraterna) to Texas (ssp. ovifera var. texana), and north through the Mississippi Valley to southern Illinois (ssp. ovifera var. ozarkana).
As recently as 250 years ago, wild populations of ssp. ovifera may have occurred throughout the Gulf coastal region and certainly in Florida.A whole different lineage of cultivars, classified as ssp. ovifera var. ovifera, evolved from eastern U.S. populations of var. ozarkana. Aborigines of the Mississippi Valley apparently were not as interested as the Mexicans in quickly selecting for large seeds or fleshy fruits. Instead, a variety of small, odd-shaped, hard, and often warty cultivars were used as containers or grown for other nonsubsistence purposes. And although the seeds of early cultivars were probably eaten, in selecting for food, natives of the eastern United States developed several cultivars, such as the precursors of the scallop squashes and crooknecks, that produced tasty immature fruits.
Gilbert Wilson’s (1917) treatise on agriculture among the Hidatsa indigenes of the Northern Plains gives us a more detailed account of the aboriginal use of C. pepo. These Native Americans cultivated squashes of various shapes, sizes, and colors together, picking them when four days old.
The young fruits were eaten fresh or sliced and dried for the winter. The flesh, and sometimes the seeds, of these mature fruits were boiled and eaten. Male squash blossoms did not go to waste either; they were picked when fresh and boiled with fat or dried for later use in mush. One fruit per plant was allowed to mature so as to provide seed for the next planting.
In addition to the two primary centers of domestication of C. pepo, a few landraces and cultivars may have been domesticated from wild populations of ssp. fraterna in northeastern Mexico.These landraces and those from southern Mexico probably spread to the eastern United States between A.D. 1000 and 1500, if not earlier. The intermingling of cultivars undoubtedly gave rise to new genetic combinations, which accounts for the diversity of fruits encountered by the earliest European visitors. The “acorn squashes,” which include the Northern Plains landrace ‘Mandan’, may have originated in this way when Mexican “pumpkins” met “scallop squashes” in the United States. Similarly, ‘Fort Berthold’ and ‘Omaha’ are northern-adapted “pumpkin” landraces that were being grown by Sioux tribes in the early twentieth century.
Fruits representing all of the major horticultural groups are pictured in the herbals of the sixteenth century. More than any other squash, C. pepo was enthusiastically embraced by European horticulturists; hundreds of new cultivars, particularly the “marrows,” have been developed in Europe and in the United States over the past 400 years. Selection practices emphasized earliness in flowering, compactness or bushiness in growth, and uniformity within a cultivar for fruit characteristics.
Although C. pepo was carried to other parts of the globe during the seventeenth century, diversification of landraces was limited primarily to the “pumpkins” of Asia Minor. Nevertheless, unique cultivars did develop elsewhere, such as ‘Alexandria’ from Egypt, ‘Der Wing’ from China, ‘Nantucket’ from the Azores, and ‘Pineapple’ from South America.
Numerous landraces of C. maxima with differing fruit characteristics can be found throughout South America today. However, archaeological remains are less widespread. Most are from coastal Peru, where the earliest evidence of domestication appears between 2500 and 1500 B.C. Later pre-Columbian remains have been found in Argentina (500 B.C.) and northern Chile (A.D. 600). Early Spaniards noted that landraces of C. maxima were being grown by the Guarani indigenes of northeastern Argentina and Paraguay.
The wild progenitor of domesticated C. maxima ssp. maxima is C. maxima ssp. andreana (Naud.) Filov, a weedy native of warm temperate regions in northern Argentina, Uruguay, Bolivia, and possibly Paraguay. Hybridization between cultivars and wild populations has contributed to genetic variability in ssp. andreana, producing wild fruits that vary from pear-shaped to oblong to round. Some landraces may have been selected from these introgressed populations.
South American aborigines apparently selected for large fruits of ssp. maxima with high-quality flesh and good storage capabilities. The largest South American fruits, weighing 20 to 40 kg, are found in landraces from central Chile. Fruits with a woody skin suitable for long storage were noted in Bolivia by Russian explorers in the 1920s. Warty fruits also evolved in South America, and in the twentieth century are found in Bolivia and Peru. Other native landraces yield tasty immature fruits.
Cultivation of C. maxima did not spread to northern South America, Central America, and North America until after the European invasion of the sixteenth century. Yankee sailors were supposedly responsible for introducing various cultivars, including ‘Acorn’, or ‘French Turban’, ‘Cocoa-Nut’, and ‘Valparaiso’, to New England early in the nineteenth century. Although all of the horticultural groups probably have their origins in South America, the spread of C. maximathroughout North America yielded some new landraces and cultivars. For example, ‘Arikara’ and ‘Winnebago’ are landraces that were grown by aboriginal tribes in North Dakota and Nebraska, respectively, during the beginning of the twentieth century. The “banana squashes” proliferated in Mexico, and “Hubbard squashes,” like ‘Marblehead’, came to the eastern United States from the West Indies during the 1800s.
Visitors took several types of C. maxima back to Europe during the sixteenth through nineteenth centuries. Some, like the turban squash called ‘Zapallito del Tronco’ or ‘Tree Squash’, came directly from South America. Most cultivars were introduced from colonial North America, but others reached Europe via Asia, Australia, and Africa, where local landraces evolved. For example, ‘Red China’ is a small turban squash that was brought to Europe from China in 1885. India also became a secondary center of cultivar diversity, particularly for the large “show pumpkin” types.Today, Indian fruits, weighing up to 130 kg, range from spherical to oblong to turban-shaped. Unusually shaped squashes with brown seeds such as ‘Crown’, ‘Triangle’, and ‘Queensland Blue’ are late-maturing Australian cultivars. And in Africa, C. maxima was so widespread by the nineteenth century that some botanists mistakenly concluded that Africa was the ancestral home of this squash.
In addition to collecting cultivars from around the globe, the Europeans succeeded in producing their own new strains, particularly in nineteenth-century France. For example, ‘Etampes’ and ‘Gray Boulogne’ entered the commercial trade in the 1880s. Selections within the “turban squashes” at this time focused on producing smaller nonprotruding crowns.
Pre-Columbian remnants of domesticated C. ficifolia have been found only in Peru, with the earliest seeds, peduncles, and rind fragments dating between 3000 and 6000 B.C.An archaeological seed from southern Mexico that was originally identified as C. ficifolia apparently belongs to C. pepo instead (cf. Andres 1990). Assuming domestication in northern South America, it is not known when this squash reached Mexico; however, it was being cultivated there in the twelfth century.
No wild species of squash exhibits the type of relationship with C. ficifolia that is expected in the pairing of a crop with its wild progenitor.Although definitively wild populations of C. ficifolia have not been identified, reports of weedy, self-sustaining plants in Guatemala and Bolivia are intriguing and need to be explored further.
As with the other domesticates, human selection produced relatively large, fleshy, nonbitter fruits with large seeds. However, the overall lack of genetic diversity in C. ficifolia relative to the other domesticated squashes suggests that human selection pressures on the former have been limited in their duration, their intensity, their diversity, and their effects.
This cool-tolerant but short-day squash did not reach Europe until the early 1800s, coming by way of southern Asia, where the long-keeping fruits were mainly used to feed livestock, especially during lengthy sea voyages. Although some accessions of C. ficifolia have been successfully grown as far north as Norway, the general failure of this species to flower beyond the torrid zone may account in part for its lack of popularity in Europe.
Squash Preparation and Consumption
In rural gardens around the globe, squash is typically planted among other crops, particularly corn, and the vines are allowed to scramble over poles, fences, walls, and other nearby structures.The plants like fertile aerated soil that drains well and lots of space, water, and sunshine. Extremes in temperature or high humidity increase vulnerability to disease. During wet weather, placing a stone or fibrous mat under a fruit lying on the ground prevents the fruit from rotting.
The immature and mature fruits, seeds, flowers, buds, and tender shoot tips and leaves of all of the domesticated squashes can be and have been eaten. Harvest of the one- to seven-day-old fruits of the summer squashes begins seven to eight weeks after planting and continues throughout the growing season. Pumpkin and winter squash fruits take three to four months to mature and are harvested only once, usually along with or later than other field crops.The best seeds are taken from the oldest fruits. Once flowering begins, open male blossoms can be collected almost daily. Leaves and growing tips are picked when needed, but only from healthy, vigorous plants.
Even though immature squashes can be eaten raw, usually they are boiled first and then seasoned to taste. In various cultures, the fresh fruits are sliced, battered, and fried; stuffed with cooked meat and vegetables; boiled and then mashed like potatoes; or added to curries or soups.The Sioux of the Northern Plains sliced fresh four-day-old fruits of C. pepo, skewered the slices on willow spits, and placed the spits on open wooden stages for drying. In Mexico and Bolivia, young fruits and seeds of C. ficifolia are sometimes blended into a mildly sweetened, alcoholic beverage made from corn mush.
The precursor of the colonial pumpkin pie was a mature pumpkin, probably C. pepo, filled with fruit, sugar, spices, and milk. Seeds were removed and ingredients added through a hole cut in the top of the pumpkin.The stuffed fruit was then baked among the coals of an open fire. In a simpler version of this recipe, prepared by aborigines as well as settlers, the fruits were baked first and then sliced and garnished with animal fat and/or honey or syrup. Pumpkin pudding, pancakes, bread, butter, dried chips, and beer have long histories rooted in colonial New England.
In other countries, mature pumpkins and winter squashes are stewed or steamed as vegetables, added to soups, candied, or stored whole or in slices for later use. A presumably ancient aboriginal use of mature fruits of C. ficifolia is in making various types of candy. Chunks of flesh are boiled with the seeds in alkali and then saturated with liquid sugar. In Indonesia, the local inhabitants create a delicacy by adding grated coconut to the boiled flesh of C. moschata. Of course, the most popular nonfood usage of pumpkin fruits (usually C. pepo or C. maxima) is for carving jack-o’-lanterns, a nineteenth-century tradition from Ireland and Great Britain.
Although the fruits of all domesticated squashes can be prepared similarly, there are culinary differences among the species with respect to the flavor, consistency, and appearance of the edible flesh. Cucurbita moschata and C. maximaproduce the strongest tasting (mildly sweet and somewhat musky) and deepest colored mature fruits; consequently, these species are favored for canning. Because fruits of C. maxima are also the richest in vitamins and finest in texture, they are mashed into baby food.Among the squashes, flesh quality in C. maxima generally holds up best when dehydrated and then reconstituted. The elongated fruits of summer squashes make C. pepo the foremost producer of easy-to-slice young fruits. Although this species dominates the commercial market, the fuller flavor of the immature pepos of C. moschata make C. moschata the preferred vegetable in rural China, the Canary Islands, and Central America.
Landraces of C. argyrosperma yield the largest edible seeds in a fruit that is otherwise unremarkable. Mature fruits of C. ficifolia are the most bland and fibrous of all squashes. However, they store longer than the fruits of the other species (two to three years versus one year) and sweeten with age. The flesh contains a proteolytic enzyme that may be of future commercial value to the food industry. Because of the stringiness of the flesh of C. ficifolia, a special Aztec confection called “Angel’s Hair” can be prepared from the boiled flesh fibers. Comparable texture in the C. pepo cultivar ‘Vegetable Spaghetti’ allows preparation of the baked or boiled fibrous flesh into a dish resembling the namesake pasta.
For commercial canning, growers have selected high-yielding cultivars like ‘Kentucky Field’ that have mature fruit flesh of the proper color and consistency. Flavor is less important as it can be controlled with spices. Consistency, which refers to the stiffness or relative viscosity of the processed f lesh, is enhanced by using fruits that are barely ripe and by adding the product of a high-consistency cultivar to that of a low-consistency cultivar. Starch, as well as soluble solids, greatly influences consistency. Because fruit storage results in the loss of carbohydrates and in the conversion of starch to sugars, freshly harvested fruits are preferred for the canning process.
Squash seeds, which have a nutty flavor, are eaten worldwide.They are consumed raw, boiled, or roasted, usually with the testa or shell removed. Mexicans grind the roasted shelled seeds into a meal, which is used to make special sauces. In China and India as well as in the New World, rural peoples make pastries from the seeds, often by covering them with syrup and then baking the mass into a type of peanut brittle. Some Chinese cultivars of C. moschata and C. maxima are grown specifically for their seeds. Similarly, various landraces of C. argyrosperma contribute heavily to the commercial production of edible seeds in Mexico.
A “naked seed” cultivar of C. pepo, called ‘Lady Godiva’, produces a seed lacking a testa.These hull-less seeds are popular snacks in the United States. In addition to food, New World aborigines have used squash seeds for a variety of medicinal purposes. A decoction serves as a diuretic and an antipyretic, the seed oil is applied to persistent ulcers, and the seeds are eaten to expel gastrointestinal parasites.Although rural communities use the seed oil for cooking as well as for medicine, the possibility of commercial extraction of the edible unsaturated oil has yet to be explored.
Aboriginal Americans, including the Aztecs, have a long tradition of eating male squash flowers and floral buds. The large orange blossoms lend seasoning and color to stews, soups, and salads and can be stuffed or battered and fried. Young leaves and shoots, which have relatively low concentrations of the bitter cucurbitacins, are also important potherbs in Mexican cooking. In India, squash leaves and growing tips are eaten as salad greens or added to vegetable curries. Nineteenth-century Indonesians prepared a dish in which fish and young leaves of C. moschata were wrapped in banana leaves and roasted under live coals.
Sixty to 85 percent of a mature fresh squash fruit is edible, as compared to over 95 percent edibility in immature fruits.The edible portion of a pepo, which is 85 to 95 percent water by weight, is lacking in most nutrients, particularly protein (0.5 to 2.0 percent) and fat (less than 0.5 percent).Carbohydrates are more concentrated in mature fruits (up to 15 percent of the fresh edible portion) than in the tender fruits of the summer squashes (less than 5 percent). Likewise, calories per 100 grams of edible fresh-weight flesh range from 10 to 25 in summer squashes versus 20 to 45 in the mature fruits known as pumpkins and winter squashes.
The most significant dietary contribution of the pepo is the relatively high concentration of carotenes, the precursors of vitamin A, in cultivars with deep yellow to orange flesh.
Particularly well studied and rich in these and other nutrients are the ‘Butternut’ and ‘Golden Cushaw’ cultivars of C. moschata and various “hubbard” and “delicious” squashes of C. maxima. As a source of vitamin A, these winter squashes compare with sweet potatoes and apricots.Although the raw flesh is higher in vitamins, a half cup of cooked mashed winter squash provides 91 percent of the U.S. Recommended Dietary Allowance (RDA) of vitamin A, 16 percent of the recommended vitamin C, 12 percent of the recommended potassium, 1.7 grams of dietary fiber, low sodium, and only 40 calories. In addition to the carotenoids, squashes are good sources of other compounds with cancer-fighting potential, including flavonoids, monoterpenes, and sterols.
For some nutrients the best source is not the fruit but other parts of the squash plant. Leaves are richer in calcium, growing tips provide more iron as well as higher levels of vitamin C and the B vitamins, and seeds contain various minerals including potassium, magnesium, copper, and zinc. Although the nutritional content of flowers has not been studied, the orange petals are undoubtedly rich in carotenes.
Seeds are the most nutritious part of the plant, containing 35 to 55 percent oil and 30 to 35 percent protein by weight. In fact, the naked seeds of ‘Lady Godiva’ are very similar in agricultural yield and nutritional content to shelled peanuts.
The edible semidrying oil of squash seeds is dark brown with a green tint and a nutty odor. About 80 percent of the oil consists of unsaturated linoleic (40 to 50 percent) and oleic (30 to 40 percent) acids.The dominant saturated fatty acid, palmitic acid, accounts for about 13 percent of oil composition. As with other oilseeds, proteins in squash seeds are rich in nitrogen-containing amino acids such as arginine but lacking in lysine and sulfur-containing amino acids. These proteins are packaged primarily in globulins called cucurbitins.Whereas the testa is highly fibrous, carbohydrates in the decorticated seeds are limited to cell wall cellulose, phytic acid, and a minimal amount of free sugars; starch is absent. Ground seeds (including the testas) are good sources of minerals, particularly potassium, phosphorus, and magnesium.