"Cucubita species: Taxonomy, terminology, description, uses and intra-specific classification. Origin and domestication. Development of cultivars".
Ferriol, M. (Doctoral Thesis). Directors: F, Nuez and B. Picó.

1. TAXONOMY AND TERMINOLOGY OF Cucurbita GENUS

The Cucurbitaceae family belongs to the monotypic order Cucurbitales, class Magnoliopsida (subclass Rosidae). The Cucurbitaceae family includes two subfamilies: Zanoniodeae, characterized by its small striate pollen grains, and Cucurbitoideae, characterized by the styles being united in a single column. The larger subfamily Cucurbitoideae is composed of seven tribes. The Cucurbiteae tribe is characterized by its pantoporate, spiny pollen. The genus Cucurbita belongs to this tribe, and includes 12 or 13 species spread throughout the Americas (Jeffrey, 1990). All the species of the Cucurbita genus contain 20 pairs of chromosomes (2n = 40). They are secondary polyploids with the base number x = 10 (Weeden and Robinson, 1990).
The plants are monoecious. The flowers are bright yellow, large, and showy, and occur singly in the axils of the leaves (Figure 1). Stamens are structured in a column in male flowers. The pistillate flowers are epigynous. The thick, short style is terminated by three, bilobed or divided, papillate stigmas. The stamens are sterile and rudimentary. The flowers open early in the morning and are pollinated by bees. The fruits of the cultivated cucurbits vary greatly in size, shape, and colour. Some of them are among the largest found in the plant kingdom. They are classified as an inferior berry, or pepo (Bailey, 1949).
The species of the Cucurbita genus have been divided into two large groups: the xerophytic species, which are perennial and have tuberous roots, and the mesophytic species, which are annuals or perennials with a short life-span and have fibrous roots. The five cultivated species of the genus are included in this last group: C. pepo L., C. maxima Duch., C. moschata Duch., C. argyrosperma Huber and C. ficifolia Bouché (Nee, 1990). These species are reproductively isolated. Merrick (1990) indicated an exception to this rule, and found a high level of fertility in hybrids between C. argyrosperma and C. moschata, when crossing specific cultivars.

Figure 1. Female flower (left) and male flower (right) of Cucurbita genus.


The terminology for the fruit in English and French is very complicated, and there are many slight differences in meaning and synonyms (Paris, 2001; Defay, 1995) (Table 1).

Table 1. English, French and Spanish terminology for pumpkins and zucchinis.


2. THE MOST IMPORTANT CULTIVATED SPECIES OF THE GENUS Cucurbita: C. pepo, C. maxima AND C. moschata.
2.1. Description, uses and intra-specific classification
2.1.1. Cucurbita pepo
C. pepo is characterized by uniformly colored tan seeds, lobed leaves with prickly pubescence, hard, roughly angled peduncles and flowers with short, thick and conical androecia (Decker-Walters and Walters, 2000) (Figure 2). It is a species that has spread all over the world and has adapted to a wide range of ecological conditions. It can be cultivated from sea level up to high altitudes and in different types of soils.
Seeds of this species, when roasted or ground in stews, are very popular as are its fruits both when mature and immature. The immature fruits of C. pepo are more popular in commercial markets than those of the other species of Cucurbita. Zucchinis belong to this type. Likewise, its flowers are preferred to the ones of C. moschata in some areas of Mexico, due to their lower pubescence and better digestion. They are consumed as a boiled or fried vegetable. In addition, the fruits of many cultivars of C. pepo that have a lignified rind can be employed as recipients. Also, the plants and fruits of this species are employed in traditional medicine and as ornamentals (Lira-Saade, 1995).
From a taxonomical point of view, C. pepo can be classified in three subspecies, established according to the allozyme variation and the morphology of its seeds and fruits (Decker-Walters et al., 2002):
1) C. pepo L. ssp. pepo,
2) C. pepo L. ssp. ovifera (L.)D.S.Decker, var. ovifera (L.)D.S.Decker var. ozarkana D.S.Decker-Walters var. texana (Scheele) D.S.Decker
3) C. pepo L. ssp. fraterna (L.H.Bailey)Andres.

The subspecies pepo includes edible cultivars and ornamental varieties of round, orange and warty fruits. The subspecies ovifera var. ovifera includes edible cultivars and ornamental varieties with oval and pear-shaped fruits. This subspecies groups two wild varieties, the var. texana, with populations distributed in Texas, Arkansas, Missouri, Alabama and Illinois, and the var. ozarkana, with populations in the Mississippi Valley and on the Ozark plateau (Decker, 1988; Decker-Walters et al., 2002). Finally, the subspecies fraterna groups the wild forms of northeastern Mexico (Andrés, 1987).

Figure 2. Distinctive features of C. pepo. a. leaf, b. bushy plant, c. long vine plant, d. mottled leaves, e. seeds, f. and g. variability in fruits and h. detail of the fruit peduncle.


Paris (1986, 1989, 2001) classified the edible cultivated types into 8 morphotypes or botanical varieties. The morphotypes “Pumpkin”, “Vegetable Marrow”, “Cocozelle” and “Zucchini” are included in the ssp. pepo, whereas “Scallop”, “Acorn”, “Crookneck” and “Straightneck” belong to the ssp. ovifera. The fruits of the morphotypes “Pumpkin” and “Acorn” are consumed when mature, aproximately 40 days after anthesis, whereas the rest of the morphotypes are consumed at an immature stage, approximately 7 days after anthesis. The morphotype “Pumpkin”, also called C. pepo L. var. pepo Bailey, has spherical to oval fruits, with round or flat ends, sometimes presenting grooves, ribs or warts, and can weigh up to 25 kg. (Figure 3). Due to its high variability, different groups have been established inside this morphotype. The typical Halloween pumpkins, cultivated in the United States and Canada, are orange and ribbed, with smooth rinds and fibrous flesh. In Mexico and Guatemala, the fruits of this morphotype are ribbed, lignified and fibrous. They are consumed when immature. The seeds, which are usually big, are also commonly consumed. Pumpkins from Europe and Asia Minor most likely derive from North American pumpkins, and they exhibit a great variability of shape, texture and hardness. Most of these fruits have a pattern of alternating yellow and green bands.
The morphotype “Vegetable Marrow”, also called C. pepo L. var. fastigata ssp. nov., is very common in the Middle East and in northern Africa. Its fruits, which have lignified rinds, are widened in the distal part and elongated, with a length/width ratio between 2 and 3.
The fruits of the morphotype “Cocozelle”, C. pepo L. var. longa ssp. nov., are long and bulbous on the distal end, with a length/width ratio higher than 3.5.

Figure 3. Morphotypes of C. pepo belonging to C. pepo ssp. pepo: a. “Pumpkin”, b. “Vegetable Marrow”, c. “Zucchini” and d. “Cocozelle”. Belonging to C. pepo ssp. ovifera: e. “Acorn”, f. “Scallop”, g. “Crookneck” and h. “Straightneck”.

The morphotype “Zucchini”, C. pepo L. var. cylindrica ssp. nov., is currently the most economically important, and it is spread all over the world. Its fruits, commonly called zucchini, are cylindrical and have a length/width ratio higher than 3.5. The former yellowish types have been currently replaced by the green ones.
The fruits of the morphotype “Scallop”, C. pepo L. var. clypeata Alefeld, are flattened, lignified, generally discoid and with scalloped edges. At present, yellow colors are preferred to white or pale green.
The morphotype “Acorn”, C. pepo L. var. turbinata ssp. nov., also known as “Table Queen”, is composed of oval to conical fruits, with 10 deep grooves. Almost all modern cultivars are green.
The fruits of the morphotype “Crookneck”, C. pepo L. var. torticollis Alefeld, are elongated with a long, thin and curved neck, and is mostly yellow and warty. The plants generally have a bushy growth.
Finally, the morphotype “Straightneck”, C. pepo L. var. recticollis ssp. nov., has fruits which are cylindrical, yellowish, warty and widened in their distal end, and which have a short peduncle constrained at their end.
In addition, other forms of C. pepo not included in the previous morphotypes have also been described. Some of them have intermediate characteristics. Other are unique, such as the cv. Delicata, possibly the only survivor of the “Fordhook” type, which, along with the types “Pumpkin”, “Scallop”, “Crookneck” or “Straightneck”, “Vegetable Marrow” and “Table Queen”, made up the intraspecific classification proposed by Castetter in 1925.

2.1.2. Cucurbita maxima

C. maxima is distinguished by its soft, round stems, whole or shallowly lobed, unpointed leaves, and fruits with spongy, enlarged, terete peduncles. The androecium is short, thick and columnar. Compared to the other domesticated species of Cucurbita, the seeds of this squash are thick, particularly in relation to their margins (Decker-Walters and Walters, 2000). The fruits are quite variable in size, shape, and coloration (Figure 4). Today, this species is grown in tropical to temperate regions all over the world, particularly in South America, Southeast Asia, India and Africa. Like C. pepo, some cultivars tolerate the relatively low temperatures of the American plains located near 3000 m above sea level (Lira-Saade, 1995).
The most important use of this species is the consumption of the mature flesh of the fruits, whose quality is the best among all the pumpkins for its flavor and richness in vitamins. The most common way of consuming the flesh is in deserts, and it is boiled or roasted. In South America, some landraces produce small fruits which are consumed at an immature stage (Nee, 1990). In the countries in which they have been introduced from America, one of the most common uses of the fruits is for feeding animals. The seeds are industrially processed. They are very rich in oil and proteins (Joshi et al., 1993). Traditionally, they are also employed in medicine, being consumed in Colombia as a vermifuge. Finally, some cultivars, like the turbaniform type, are used as ornamentals (Lira-Saade, 1995).

Taxonomically, the species C. maxima is divided into two subspecies:

C. maxima Duch. ssp. maxima
C. maxima Duch. ssp. andreana (Naud.)Filov

C. maxima ssp. maxima includes the ornamental and cultivated forms. C. maxima ssp. andreana includes only the wild forms, and it is considered to be the ancestor of the cultivated forms. This subspecies is endemic to the temperate areas of Argentina, Uruguay, Bolivia and probably Paraguay. Hybridization between wild and cultivated types has contributed to increase the genetic variability of the subspecies andreana, whose fruits can be pear-shaped, oblong or rounded (Decker-Walters and Walters, 2000).

Figure 4. Distinctive characteristics of C. maxima. a. leaf, b. plant, c. and d. variability of seeds, e. detail of fruit peduncle and f. morphological variability of fruits.

The varieties of C. maxima used in American and European trade fit into the classification proposed by Castetter (1925) (Whitaker y Davis, 1962; Robinson and Decker-Walters, 1997; Decker-Walters and Walters, 2000). The “Banana” type includes long fruits which are pointed at both ends, with a soft rind and brown seeds. Plants of this type can tolerate high temperatures. The fruits of the “Delicious” type are turbinate-shaped and have shallow ribs, a hard rind, white seeds and a high quality flesh. The “Hubbard” type includes oval fruits, with pointed or curved ends, a very hard rind and white seeds. Fruits of the “Marrow” type are early, oval or pear-shaped, bulbous and have white seeds. Fruits of the “Show” type are wide and orange-colored with a smooth rind and white seeds. This type presents a high variability in India, where they are used mainly to feed animals. Finally, the “Turban” type includes turbinate-shaped fruits.

However, not all the cultivars can be included in the previously described types. There are commercial varieties and landraces with intermediate or different characteristics.

2.1.3. Cucurbita moschata
C. moschata is distinguished by its big flowers, with long slender androecia, foliaceous sepals, relatively soft pubescence on the foliage, mottling leaves, and distinctly-colored seed margins. The peduncles are compact and flared (Decker-Walters and Walters, 2000). The fruits are highly variable in size, shape, ribbing and rind texture (Figure 5).
Among the domesticated species, C. moschata best survive in the hot, humid, low-elevation (usually under 1500 m above sea level) climates of the mid-latitudes. However, some fruits and seeds have been collected in Mexico and Colombia up to an altitude of 2300 m above sea level (Lira-Saade, 1995).

Like C. maxima, the fruits of C. moschata are preferably eaten at a mature stage, its flesh being of high quality. Its seeds are also consumed in many parts of Mexico and Central America, as it is one of the most popular species for the great number and size of its seeds. Immature fruits, male flowers, and vegetative buds are also edibles (National Research Council, 1989). On the other hand, plants of C. moschata are also used as rootstocks for its resistance to diseases and abiotic stresses, for the winter cultivation of watermelon, melon and cucumber, and it is one of the most promising species (Traka-Mavrona et al., 2000). In addition, the whole plant and its fruit are employed in traditional medicine (Lira-Saade, 1995).

Figure 5. Distinctive characteristics of C. moschata. a. and b. morphological variability of leaves, c. plant, d. fruit peduncle, e. morphological variability of fruits and f. seeds.

Filov (1966) classified more than 20 varieties of C. moschata into geographical subspecies. This classification revealed the existence of important centers of diversity, like Colombia, where varieties with small fruits and dark seeds are abundant, Japan, with fruits frequently covered in warts, Mexico, Central America, the western United States, Florida, India and Asia Minor. Unfortunately, many of these landraces had not been introduced in U.S. and European markets, where only three groups of cultivars are commercialized (Whitaker y Davis, 1962; Robinson y Decker-Walters, 1997). The “Cheese” type includes fruits which are variable in shape, mostly oblong, and have a leather-colored rind. Its plants are vigorous and high-yielding, and are adapted to different growing conditions. Fruits of the “Crookneck” type have a rounded distal end and a long straight or curved neck. Finally, the “Bell” type presents fruits with a shape which ranges from flared to almost cylindrical (Figure 6).

Figure 6. Groups of C. moschata established in America and European markets. From left to right: “Cheese”, “Crookneck” and “Bell”.


2.2. Origin and domestication
2.2.1. Cucurbita pepoThe oldest known archaeological remains of cultivated Cucurbita species belong to C. pepo. Smith (1997) considered the remains of seeds and peduncles of fruits of C. pepo ssp. pepo cultivated in Oaxaca (Mexico) to be almost 10,000 years old. So the domestication of C. pepo may have preceded other American crops like corn and common beans by more than 4000 years. Other archaeological remains evidence the cultivation of C. pepo in southern and northeastern Mexico and in the eastern United States more than 4000 years ago, covering different ecological niches, from the high plains to fluvial systems. Later, this crop spread to the western United States (1000 B.C.) (Decker-Walters y Walters, 2000; Decker-Walters et al., 2002).

The distribution of the archaeological record of C. pepo over a wide area and the grouping of allozymic patterns of the cultivated forms in two clearly defined subspecies suggested the existence of two independent domestication events (Decker, 1985). This hypothesis was later supported by additional allozymic assays, comparisons of chloroplastic and mitochondrial DNA, as well as RAPD markers (Kirkpatrick and Wilson, 1988; Wilson et al., 1992; Decker-Walters et al., 1993; Sanjur et al., 2002; Decker-Walters et al., 2002).

Initially, allozymic studies lead to the proposal of the species C. texana A. Gray (today classified as C. pepo ssp. ovifera var. texana), located in the fluvial systems of Texas, as the possible ancestor of C. pepo ssp. ovifera. Its morphological characteristics are very similar to those of the ornamental cultivars of the subspecies ovifera (Striped Pear) and both are sexually compatible, although the seed morphology and the allozymic patterns differ between them (Decker, 1988; Kirkpatrick and Wilson, 1988; Nee, 1990). According to Heiser (1985), the texana variety could have had a wider distribution than the one it has today. After its independent domestication in the United States and Mexico, the variety texana might have disappeared from the majority of its geographical spread due to a generalized growing of the cultivated form, destruction of its habitat or hybridization with cultivated types. However, in spite of the existence of the archaeological remains of domesticated forms of C. pepo, Ford (1985) pointed out that the cultivation of this species was not very widespread in prehistoric times. Therefore, it could be that the texana variety wasn’t domesticated, but instead its fruits were collected for use as containers (Decker, 1988). On the other hand, the existence of spontaneous populations of this variety in other states suggests the possibility that the texana variety is the escape of a crop (Kirkpatrick et al., 1985; Decker, 1988; Kirkpatrick y Wilson, 1988). Kirkpatrick and Wilson (1988) suggested that one of the domestications could have been produced from an ancestor similar to the texana variety which today is extinct. This ancestor could have been domesticated initially due to its utility as a container. Just as occurred with Lagenaria siceraria (Mol.) Stand., these populations could have spread to some areas of Mexico and the eastern United States.

Later, the fruits could have been selected independently to create edible forms. Subsequently, edible and wild types growing together in restricted areas may have hybridized and diferentiated, giving rise to the two edible subspecies of C. pepo and to its current wild forms, which still exist in Mexico, Texas and the eastern United States. On the other hand, Nee (1990) suggested that the wild form C. pepo ssp. fraterna, which has a short life cycle and populations of non-bitter fruit flesh, could be the ancestor of C. pepo ssp. ovifera var. ovifera. According to this hypothesis, Wilson et al. (1992), from comparisons of chloroplastic DNA, observed that C. pepo ssp. ovifera grouped with the texana variety and the subspecies fraterna, whereas C. pepo ssp. pepo did not group with any known wild species.

Today, besides C. pepo ssp. ovifera var. texana and C. pepo ssp. fraterna, a new wild species related to the variety ovifera is known: the variety ozarkana, located in the American states of Arkansas, Illinois and Missouri. Decker-Walters et al. (2002), starting with studies conducted with RAPD markers, considered that this new variety could be the possible ancestor of the ssp. ovifera var. ovifera. From isoenzyme studies, Decker-Walters et al. (1993) suggested that the three wild forms of C. pepo ssp. ovifera that had been described differentiated before their domestication. However, by comparing the mitochondrial DNA, these wild forms grouped together (Sanjur et al., 2002). These authors think that the ssp. fraterna could be the most probable ancestor of the ssp. ovifera var. ovifera due to its higher genetic affinity.

Regarding the possible wild ancestor of C. pepo ssp. pepo, some authors consider it to be unknown or extinct (Wilson et al., 1992; Decker-Walters et al., 2002). Decker (1985) suggests the ssp. fraterna as a possibility, due to its location on the muddy or volcanic plains of northeastern México. According to this hypothesis, Sanjur et al. (2002) suggest that the ssp. fraterna could have been spread in the past in small and half-isolated populations which were genetically divergent. In this way, some populations still not collected, could be the possible ancestors of C. pepo ssp. pepo.

On the other hand, the domestication process could have been different in both subspecies. The first use of the fruits of the ssp. pepo could have been the consumption of its seeds, very nutritive and non-bitter. If a selection by seed size was conducted, a simultaneous selection for bigger fruits would probably have also been done. Subsequently, mutants of non-bitter flesh might have appeared, and the selection for a lower lignification of the rind, absence of tendrils and better fruit quality would have been undertaken (Paris, 1989). Regarding the ssp. ovifera, it seems that the aborigines of the Mississippi Valley employed small pumpkins as containers or for other nonsubsistence purposes. The seeds of these pumpkins were probably edible. Then, the selection for edible fruits could have been conducted from the precursors of the “Scallop” and “Crookneck” morphotypes, which produce very tasty immature fruits (Decker-Walters y Walters, 2000). Following its domestication, C. pepo experienced a great diversification through Europe and Asia (Decker, 1988).

2.2.2. Cucurbita maxima

The earliest archaeological remains that provide evidence for the domestication of this species have been found in the coastal region of Peru (2000 BC). South American aborigines apparently selected for large fruits of ssp. maxima with a high-quality flesh and good storage capabilities (Decker-Walters y Walters, 2000). C. maxima had already been cultivated in pre-Columbian times in northeastern Argentina and Paraguay by the Guaranis as well as in the Andean Valleys. Today, there is no doubt that the wild ancestor of the cultivated form is C. maxima ssp. andreana, endemic to South America, although initially C. ecuadorensis Cutler&Whitaker, located in the coastal regions of Ecuador, was not discarded (Lira-Saade, 1995). Wild populations of the ssp. andreana grow in the temperate regions of Argentina, although some plants have also been observed on the central plains of Bolivia, for which some authors extend the putative area of domestication to this region (Sanjur et al., 2002).

2.2.3. Cucurbita moschata

The earliest archaeological remains indicative of the domestication of C. moschata were discovered in Ecuador (5170 to 3780 BC), on Panama’s central Pacific coast (5,000 BC), southern Mexico (5000 BC), in coastal Peru (3000 BC) and in Guatemala (2,000 BC). Ancient Peruvian specimens differ from those from Mexico by having a warty rind and a pronounced fringe along the seed margins. In the southeastern United States, the earliest known remains are 2,300 years old (Decker-Walters and Walters, 2000; Piperno et al., 2000).

Initially, the earliest known remains of C. moschata came from Mexico, which caused this area to be considered the center of domestication for this species (Whitaker and Davis, 1962; Esquinas-Alcázar y Gulick, 1983). Today, the archaeological record and the great diversity of forms found in South America point to this area as the center of domestication for this species or as a secondary center of early diversification (Nee, 1990; Wessel-Beaver, 2000; Sanjur et al., 2002). Some primitive characteristics have been found in landraces from Colombia, Panama and Bolivia. Some of these characteristics are dark-colored seeds, small fruits, a lignified and warty rind, long vine and indeterminate growth habits and small leaves (Wessel-Beaver, 2000). Some bitter-flavored fruits have been found in Colombia, suggesting the hybridization of cultivars of C. moschata with some wild local species (Nee, 1990). Other authors have even suggested the existence of two independent domestications in Mexico and northern South America. This hypothesis is supported by the fact that C. moschata is known by native names in both regions (Lira-Saade, 1995; Robinson and Decker-Walters, 1997; Decker-Walters and Walters, 2000).

The confusion about the center of domestication of this species is complicated by the absence of known wild relatives of C. moschata. The species C. lundelliana L.H.Bailey, confined to the mud plains of the Yucatan Peninsula, which was initially proposed as a possible ancestor of C. moschata, does not appear to be related to it in morphological, isozymic and crossability studies (Merrick, 1990). Today, given the close evolutionary relationship between C. moschata and C. argyrosperma, according to morphological and ecological studies as well as comparative mitochondrial, ribosomal and chloroplastic analyses (Wilson et al., 1992; Jobst et al., 1998; Sanjur et al., 2002), it is proposed that the ancestor of C. moschata might have derived from a wild taxon of C. argyrosperma ssp. sororia. However, the two species have different isoenzymatic patterns and crossability barriers (Sanjur et al., 2002). The recent discovery of some wild pumpkins found in Bolivia could be a key factor in the study of the origin of C. moschata (Decker-Walters y Walters, 2000).

2.3. Crop spread and the development of cultivars
2.3.1. Cucurbita pepo

The morphotypes “Pumpkin”, “Scallop” and “Acorn”, as well as some cultivars consumed when immature and some ornamental types, were already cultivated in America in pre-Columbian times, as demonstrated by the great variability found in the first European herbariums that include species from America (Paris, 1989; Paris, 2001). “Pumpkin” is probably the oldest and most diverse morphotype. Its soft rind allowed the pumpkin to be easily cut and natives most likely dried the slices in the sun to preserve them. The morphotype “Scallop” appeared in herbariums of 1554, spreading into Europe some years after “Pumpkins”. Today, a great part of its production is obtained with hybrid cultivars, which are early, bushy and have bright, colorful fruits. The morphotype “Acorn” appears in herbariums 30 to 50 years after “Pumpkin” and “Scallop”. Although representations of some cultivars seem to indicate that they were already cultivated in pre-Columbian times, its later appearance suggests that it could have been derived from a fortuitous cross between “Pumpkin” and “Scallop” cultivars. The first specimens had slighter ribs and softer grooves than the current ones. The first known cultivar was “Table Queen”, developed in the United States in 1927.

The morphotype “Crookneck” also seems to be native to America, as its cultivation was first reported in the United States, and it was probably already cultivated in pre-Columbian times. The lack of this form in the first European herbariums could have been due to the early loss of its typical characteristics due to hybridizations with other types or to its cultivation in inaccessible areas of North America, which could have delayed its arrival to Europe. Descriptions of “Crookneck” forms sporadically appeared in Europe, but it was in 1828 when it was firstly mentioned with its typical form in a seed catalogue of North America with the name of “Summer Crookneck”. The morphotype “Straightneck” appeared in herbariums towards 1700, although it is not mentioned as such until the second half of the 19th century, after the morphotype “Crookneck”. Some studies of isozymes and seed morphology show the derivation of “Straightneck” from “Crookneck”. The first commercial cultivar was developed in 1896 and one of the most popular, “Early Prolific Straightneck”, was derived from the cultivar “Summer Crookneck” in 1938.

After the arrival of the different cultivars to Europe, the forms of C. pepo, which were geographically isolated in different areas of Central and North America, were cultivated together in European gardens. Hybridization was unavoidable, producing some attractive recombinants that were quickly selected and which constituted new groups of cultivars, especially those with an elongated shape.

In this diffusion process, the role of bridge that Spain played between America and Europe is remarkable. Spain spread cultivars of this species to Europe, where they were diversified and improved. Later, some of the new types were taken to America at the beginning of the 19th century. Thus, the morphotypes “Vegetable Marrow”, “Cocozelle” and “Zucchini” may have been derived from primitive Mexican “Pumpkins” with a hard green rind, selecting them for elongated shape. Another possibility is that the morphotype “Vegetable Marrow” comes from a cross between a pumpkin cultivar with a soft rind and an elongated and pear-shaped ornamental cultivar, like “Pear”. Some of the possible precursors of the morphotype “Vegetable Marrow” are described in the herbariums of the 16th and 17th centuries, although this morphotype is not mentioned as such until the 18th century, appearing for the first time in a North American seed catalogue in 1824. Since its development, this morphotype has suffered a great genetic erosion, having been replaced by more yielding hybrids. The morphotype “Cocozelle”seems to have been developed in Italy, due to the great number of Italian towns and provinces that give their names to most of the cultivars of this type known around the world. A possible precursor of this morphotype was described in 1651. Later, around the middle of the 19th century, “Cocozelle” cultivars were developed and improved in America. Today, this morphotype exhibits the greatest morphological variability, and many cultivars can be found in the Mediterranean basin. The morphotype “Zucchini”, developed in Italy, is the most recent, being mentioned for the first time in 1856. Its fruits were introduced in the United States in the 20’s, where they were improved. Today, most of the cultivars of this morphotype are hybrids.

Currently, the morphotypes of the subspecies ovifera are of great economical importance in the United States and Canada, but not in the rest of the Americas nor on other continents. Only the fruits of the morphotype “Scallop” have a certain economical importance outside of North America.

2.3.2. Cucurbita maxima

Unlike C. pepo, there exist only few studies about the origin and evolution of the different types of cultivars of C. maxima. It is known that the cultivation of this species did not spread outside South America until the arrival of the European invasion. Starting in the 16th century, several types of C. maxima, such as the turban types, came directly from South America to Europe. Many other cultivars reached Europe via Australia, Africa and Asia, where local landraces evolved. At the beginning of the 19th century, American sailors were responsible for introducing several cultivars into the United States from South America. It would seem that all the types included in international trade come from this area. To this effect, it is known that the “Banana” type was introduced into the United States from Mexico and that the “Delicious” type was introduced from Brazil at the end of the 19th century, whereas the “Marrow” type was most likely developed in Chile (Decker-Walters y Walters, 2000). As previously discussed, there exists a great variability of C. maxima types that cannot be included in the established commercial forms. Unfortunately, very little is known about their origin and current distribution.

2.3.3. Cucurbita moschata

After its domestication, probably due to the good flavor of its seeds, C. moschata spread through the Caribbean Islands giving rise to various native cultivars (Robinson y Decker-Walters, 1997; Piperno et al., 2000). Later, after the arrival of the Spanish to America, C. moschata spread quickly to the remainder continents, adapting to different ecological conditions. The cultivar denominated “Seminole” was developed by the Seminole Indians. This cultivar still exists today. C. moschata was already cultivated at the end of the 17th century in western Mississippi, and in the 19th century in India, Java, Angola, Northern Africa and Japan, where the species diversified (Sauer, 1993; Lira-Saade, 1995; Decker-Walters and Walters, 2000). There exists no picture nor description that demonstrates the cultivation of C. moschata in Europe before the 17th century. This delay in the introduction in Europe is probably due to its bad adaptation to the long summer days typical of temperate climates (Paris, 2000).

Like C. maxima, there exists very little information about the development and history of the different types of cultivars of C. moschata. Some cultivars with concrete characteristics were developed in the different centers of diversity of this species. In Colombia, the traditional cultivars are small-sized and have dark seeds. The aborigines of Florida developed an oval or pear-shaped, small-sized cultivar named “Seminole Pumpkin”. In Japan, fruits with a warty rind are abundant, whereas in India big fruits with a soft rind are preferred, and in Asia Minor elongated and pear-shaped fruits are the most common (Decker-Walters y Walters, 2000). However, in commercial cultivars, the pear shape derived from the “Crookneck” form. The first “Butternut”, one of the most important cultivar in international trade, was generated from “Crookneck” in the thirties (Mutschler y Pearson, 1987).

Currently, the cultivars of C. moschata represent a large percentage of the winter squashes cultivated in the western United States, the central plains of Central America and the tropical countries of South America (Nee, 1990). C. moschata is also one of the most important vegetables cultivated in Zambia, Malawi and tropical Africa, where its cultivation is mainly based on landraces with a high degree of autogamy (Gwanamma et al., 2000). In spite of its late introduction into Spain, it is currently a species of similar economic importance to C. maxima. Numerous types of cultivars of C. moschata were developed in Spain which subsequently spread to Europe.


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