90 – II.2. SQUASHES, PUMPKINS, ZUCCHINIS, GOURDS (CURCURBITA SPECIES)
all other mesophytic Cucurbita species. More work is needed to decipher the relationship
of C. ficifolia to the xerophytic species of the genus with which it shares some
morphological features.
Centres of origin and distribution
All of the Cucurbita are native to the Americas. The centres of origin and
domestication for cultivated Cucurbita species can be identified as various areas in North
and South America (Jeffrey, 1990). Table 2.1 lists the natural distribution for both
cultivated and wild Cucurbita species. At least five species of the genus Cucurbita were
domesticated before the European contact in the late 15th century, forming important
food sources in Native American economies, and some of these species were among the
earliest plants taken under cultivation and domestication in the New World (Smith, 2001;
Sanjur et al., 2002).
Cucurbita argyrosperma
The natural distribution of C. argyrosperma ranges from the southwestern
United States through Mexico into Central America (Table 2.1). The area of
domestication for C. argyrosperma is considered to be from the southwestern
United States to the centre-south region of Mexico (Merrick and Bates, 1989).
Archaeological remains of C. argyrosperma found from southwestern United States to
the centre-south region of Mexico suggest that domestication of this species occurred in
the region several thousand years ago (Table 2.2). Unlike the other cultivated Cucurbita
species, data on the distribution of C. argyrosperma outside the Americas are scarce and
there is some question as to whether this species was cultivated at any time in other parts
of the world. Today, it is cultivated primarily in South America, Mexico, and on very
limited areas in the United States.
Cucurbita ficifolia
The natural distribution of C. ficifolia ranges from the Mexican highlands south to
northern Chile and Argentina (Table 2.1). It grows as an annual in temperate climates and
can appear to be a perennial in tropical zones. The precise location of the centre of
domestication of Cucurbita ficifolia is still uncertain. Some have proposed that its centre
of origin is Central America or southern Mexico/Central America. Linguistic evidence
tends to support this hypothesis because of the wide use of names based on the Nahuatl
name “chilacayohtli” as far south as Argentina. Others suggest that its centre of
domestication is located in South America and, more specifically, in the Andes (Nee,
1990). Andres (1990) compared diverse types of evidence and was not able to determine
precisely the probable domestication site of this crop. So, while native names from
indigenous Nahua influence like “chilacayote” and “lacayote” suggest a Mexican origin,
systematic evidence has been inconclusive because a strong reproductive incompatibility
has been found between C. ficifolia and the wild taxa of Cucurbita native to Mexico.
While archaeological evidence favours a South American origin since the most ancient
remains have been found in Peru (Table 2.2), it has not been possible to support this
evidence by means of systematic studies, including those involving the two wild
South American taxa (C. maxima ssp. andreana and C. ecuadorensis) as both prosper in
habitats different from those in which C. ficifolia is cultivated (Nee, 1990). Also, the bee
Peponapis atrata, until recently considered a pollinator specific to C. ficifolia, has not
been found in South America. Cucurbita ficifolia differs in its karyotype from all other
