Thomas W. Whitaker

History and Distribution of the Cultivated Cucurbits in the Americas

All species of Cucurbita (which includes squashes, pumpkins, and the common, small, yellow-flowered gourds) are native to the Americas. Their center of origin lies in Mexico where most of the 26 wild and cultivated species still grow. Chilicayote (C. ficifolia ), a perennial and probably the oldest cultivated species, is grown from Mexico to Bolivia and known archaeologically only from coastal Peru (3000 B.C.). Oldest archaeological cucurbits are C. pepo and Lagenaria siceraria , the bottle gourd. Specimens of these species were recovered from Tamaulipas in cave material dated 7000-5500 B.C. Pepo and Lagenaria spread over most of the United States probably with the advent of agriculture. Cucurbita moschata appeared in coastal Peru at the same time as C. ficifolia (3000 B.C.), but it does not occur in the Ocampo Cave cultures until 1400-400 B.C. when pottery and village life entered, and corn, cotton, pepo, and beans (common, lima and jack) were being grown. While the earliest dates for moschata in southwestern United States are about A.D. 1100, it probably entered the same time as cotton, perhaps as early as A.D. 700. Cucurbita mixta , the cushaw, is the most recent of the cultivated species. It is found mainly in Mexico and in post-A.D. 1000 sites in the southwestern U.S. Prehistoric C. maxima is known only from Peru and to the south and east in Chile and Bolivia. Its ancestors probably were carried there by man from the Mexican center, and the weedy C. andreana may have been taken along at the same time. The bottle gourd is most variable in the Old World. It probably originated there, and was carried to the New World in pre-agricultural times by ocean currents. A number of other cucurbits and the tree gourd, Crescentia cujete , not a true gourd but a member of the family Big-noniaceae, are briefly mentioned. Parts useful in identifying the cultivated cucurbits are the fruit stem or peduncle, seeds, rind, and leaves. A list of the collections of Cucurbita and Lagenaria which have been studied is given, with estimates for the date of each site.

Cytological and Phylogenetic Studies in the Cucurbitaceae

1. The chromosome numbers of 12 species of the Cucurbitaceae have been determined from pollen mother cell material. The results may be summarized as follows: Melothria punctata, n = 12; Melothria abyssinica, n = 12; Momordica balsamina, n = 11; Luffa cylindrica, n = 13; Ecballium elaterium, n = 12; Citrullus colocynthis, n = 11; Cucumis myriocarpus, n = 12; Cucumis melo var. Golden Beauty, n = 12; Benincasa cerifera, n = 12; Cucurbita melanosperma, n = 20; Cucurbita pepo var. Orange gourd, n = 20; Cyclanthera pedata, n = 16. 2. The results of an experimental study of the fertility relations involving 4 genera and 8 species of the Cucurbitaceae indicate that species crossing is comparatively rare and not at all in accord with popular beliefs. Three species crosses were obtained: (1) between Cucurbita moschata and C. maxima; (2) between Cucurbita pepo and C. moschata; and (3) between Citrullus vulgaris and C. colocynthis. 3. The technique of making controlled pollinations among members of this family has been described. 4. The pertinent points in regard to chromosome number and geographical distribution are: (a) the Old World genera, with one exception, have basic numbers of 11-13; (b) there is a New World group having 16 as the basic number; and (c) there is a second New World group having 20-24 as the basic number.

The taxonomy, genetics, production and uses of the cultivated species of Cucúrbita.

Hundreds of varieties in the five recoǵnized species of this ǵenus, all native to the Americas, are the sources of the well known pumpkins and squashes, of which about 150,000 tons, fresh weiǵht, in 481/2 million No. 2 cans, is the annual canned pack alone in the United States. The seeds constitute a potential but so far wholly undeveloped source of valuable oil.

Cucurbits and Cultures in the Americas

Summary1.The bottle gourd,Lagenaria siceraria, and the five cultivated species ofCucurbita are the cucurbits commonly found in archeological sites.2.The archeological history of the bottle gourd indicates that it was one of the first plants to be domesticated in the Americas. In many sites, it is found in pre-ceramic, pie-maize strata. In the Old World,La-genaria was never so widely distributed nor used as in the Americas, probably because of the early invention of pottery in Asia.3.The center of distribution of the genusCucurbita is apparently in the region directly south of Mexico City. In this general area, there are several wild species that are compatible with the cultivated species.4.The cultivated species ofCucurbita, in general, are characterized by an allopatric distribution. The archeological record suggests that each species was domestitcated at different times and almost certainly in different areas.5.The cultural history of the cucurbits indicates a very strong tendency towards conservative crop husbandry among pre Columbian and post-Columbian peoples in that they tended to grow essentially the same cultivars over long periods of time.

Food plants in a Mexican market

Summary1.A list has been compiled of the species of food and container plants found in the market at Tehuacán, Puebla, Mexico, during a 10-day period in March, 1962. The list comprises 83 species; 56% are New World and 42% Old World, while 2% are common to the tropics of both hemispheres. About 28% of the total number of species are thought to be Mexican endemics.2.The extensive use made of native food plants suggests that the people of the Tehuacán Valley rely heavily on this resource as a supplement to their dietary regimes.3.Mexican markets may be utilized as a tool to trace the history of cultivated plants. Ethnobotanical observations suggest that some of the plants found in the market today are retentions from earlier civilizations. This argument is illustrated by a comparison of the cultivatedCucurbita from caves in the Tehuacán Valley with the cultivars found in the market at the present time.

Plant Material from a Cave On the Rio Zape, Durange, Mexico

Plant remains from La Cueva de los Muertos Chiquitos consist mostly of cultivated plants, beans, corn, and cucurbits. The inhabitants also gathered acorns, piion nuts, black walnuts, and opuntia fruits for food, and used yucca, agave, and possibly cotton for fibers. The beans are unusually abundant and diverse: three species and 12 types or varieties. A type of lima bean (Phaseolus lunatus) and two common beans (P. vulgaris), one of them similar to the cultivar Wells Red Kidney, are new to the Southwest and to northwestern Mexico. The lima bean is of interest because it belongs to the round-seeded Carib group with a center of diversification in the West Indies, whereas other lima beans from the prehistoric Southwest are mostly small-seeded and flat, probably derived from Central America. Five races of corn are represented: an ancient race called Chapalote; Cristalina de Chihuahua, the most numerous race in the collections; Onavefio, a race with medium-sized, hard-flint kernels; Pima-Papago, the common soft flour corn of the Arizona-Sonora border; and Toluca Pop, a central Mexican pyramidal, pointed popcorn. Cob fragments and grains show definite evidence of hybridization with Tripsacum or teosinte. Three species of cultivated Cucurbitaceae, a wild species of Cucurbita, and a species of Apodanthera were identified. Fragments of gourds, mostly Lagenaria siceraria, are relatively abundant. Seeds and peduncles of Cucurbita pepo occur in strata throughout the entire profile. Cucurbita mixta was found in the later strata, but remains of this species are meagre. Seeds of Apodanthera sp. may have been used for food. A single wood sample from near the base of the midden produced a radiocarbon date of A.D. 660 (1300 ? 100 B.P.). THE ARTIFACT and plant material described in this report was collected from an archaeological cave site overlooking the Rio Zape, in the vicinity of the pueblos of El Zape and Zape Chico (Fig. 1). This area is located on the eastern slopes of the Sierra Madre Occidental in the municipio of Guanacevi, Durango, Mexico. The elevation is about 6000 feet, although to the north and west the Sierras rise to heights of 7000 to 8000 feet. The Rio Zape is the major river of this region. At a lower elevation it joins the Rio del Oro, and after junction with the Rio Ramos, becomes the Rio Nazas. A little over one mile north of the town El Zape, the Rio Zape loops and flows against the base of a series of cliffs, which rise about 100 feet above the river. The cliffs are composed of rhyolitic tuff and volcanic agglomerate rock (Brand 1939: 91). The excavated cave, along with a number of other caves, has been eroded from the rhyolitic tuff material where it contacts the harder volcanic agglomerate layer, which forms the upper stratum of the cliff. The entrance of the cave, about 50 feet above the stream bed, is reached from a trail which runs slightly below the openings of most of these caves. This trail is one of those connecting Zape Chico, a quarter of a mile to the northeast, and El Zape, over a mile to the south. Winters are not generally severe. Most people remember one foot of snow as being the maximum amount to fall in the last ten to 15 years. Summer temperatures can be quite warm averaging well over 90? F., and as in all of Mexico, summer is the rainy season. Rainfall in the area averages from 25 to 30 inches for a good year (Tamayo 1949). Insufficient rainfall, causing drought conditions, has occurred frequently in the summer seasons over the last 30 years. Despite variation in the local rainfall, however, the Rio Zape flows the year round. Brand (1939: 77) has described the area as a mesothermal savannah (CW) and a hot steppe (BSh). The vegetation includes pifion pine, several species of oak, juniper, a number of genera of cacti, several species of agave, grasses and the ever present gatuna or cats claw. Along the river bottom grow cottonwoods, willows, and an occasional black walnut tree. Locally, coyotes, jackrabbits, squirrels, mice, rats, and other small animals compose the present day fauna. Evidence from the cave indicates all of these animals were hunted in the past. In addition, deer, and possibly mountain sheep were a source of food. At the present time the latter are found only in the remote mountain regions to the west. Several species of fish and numerous small turtles live in the Rio Zape and their remains were also found in the midden of the cave site. The fish bones were identified by Robert R. Miller, University of Michigan: The fish bones from the Rio Zape Cave include vertebrae, pharyngeal bones, and part of a Weberian apparatus belonging to three families of fishes: minnows (Cyprinidae), suckers (Catostomidae), and catfishes (Ictaluridae). The minnow undoubtedly represents Gila and probably G. conspersa (Garman), the Nazas chub. The suckers comprise two species, not positively identified, but possibly referable to the genera Carpiodes and

Pre-historic Cucurbits from the Valley of Oaxaca'

About 180 specimens of cucurbits were recovered from the Guila Naquitz Cave in the Valley of Oaxaca, Mexico, from strata dated at 8750-7840 B.C. to 1500 A.D. by Carbon- 14 analyses. 4 Almost 60% of the cucurbit specimens were of wild species of Cucurbita. A single seed may be that of the perennial squash or fig- leaf gourd, C. ficifolia Bouch é. All other cultivated squash material was C. pepo L., the summer squash. Cucurbita pepo prefers cool, dry environmental conditions. This suggests that farmers utilized the cave on a seasonal basis, because cultivars of C. pepo mature later and store better than those of C. moschata Poir. or C. mixta Pang., which would normally be the species expected to be cultivated at this latitude. Specimens of bottle gourd, Lagenaria siceraria (Mol.) Standl., were comparatively rare and comprised only 10% of the total. The scarcity of bottle gourd remains suggests that these gourds were not important for containers and household, use even in preceramic levels, or that they simply did not break many of their vessels during the limited time they occupied the cave. A second possibility is that agriculture was carried out at higher and cooler elevations, which C. pepo prefers but which are unfavorable for Lagenaria. A few Apodanthera seeds were found at all levels.

A numerical taxonomic study of Cucurbita

Several statistical techniques of numerical taxonomy were studied by using 21 species ofCucurbita as models. Data were taken on 93 plant characters for 24 operational taxonomic units (OTU’s). Three similarity coefficients, Q-correlation, distance and divergence, were used to compute phenetic similarities among the 24 OTU’s. The results are summarized in the form of eight phenograms using both unweighted and weighted pair-group methods of clustering. The results obtained from the various statistical techniques were compared with cross-compatibility ratings. The distance and divergence coefficients and their respective phenogram values were more highly correlated with the cross-compatibility ratings than were the Qcorrelation coefficients and their phenogram values. However, from a subjective viewpoint, the phenograms derived from Q-correlation coefficients were in closer general agreement with a combination of biological factors including cross compatibility, geographical distribution, and ecological adaption than were phenograms derived from distance or divergence coefficients.

Genetic control of leucine aminopeptidase and esterase isozymes in the interspecific cross Cucurbita ecuadorensis X C. maxima

Starch gel electrophoretic analyses of crude seed extracts of Cucurbita ecuadorensis, C. maxima, their F1 and F2, and three of the four possible interspecific backcrosses reveal that the genus is polymorphic for alpha-naphthyl acetate esterases (Est) and leucine aminopeptidase (LAP). The two electrophoretic forms of both Est and LAP are controlled by codominant alleles. The two loci do not exhibit linkage. Neither the LAP nor the Est phenotypes exhibit a significant deviation from the expected 1:1 ratio in interspecific backcrosses when the donor parent alleles are transmitted through female gametes, but there is a significant deviation for Est when transmission is through male gametes. Differential gametic selection involving the Est-1 locus suggests structural differences between the genomes of the parental species for the chromosomal region in which this locus occurs. No structural differences are indicated between the parental genomes for the chromosome region bearing the Lap-1 locus.

Salads for everyone—a look at the lettuce plant

SummaryIf we examine in detail the origin, domestication and breeding system of cultivated lettuce, the following conclusions emerge:1.The group of species from which lettuce originated is indigenous to the eastern Mediterranean Basin, probably Egypt.2.Lettuce was most likely domesticated in Egypt, moving at an early date to Rome, Greece and later to China. It moved to the Americas shortly after their discovery, and as early as 1806 seedsmen listed more than a dozen cultivars from the United States.3.Lettuce is a self-fertilized species which, under cultivation, has produced an abundance of variation, mostly in leaf size, shape, texture and color, and the arrangement of the leaves on the stem.4.Variation in lettuce can be accounted for by early interspecific hybridization, and the protection of many mutants undesirable under natural conditions, but favorable under cultivation.5.An analysis of the characters that separate these two species indicates thatL. sativa could be derived fromL. serriola by intensive selection.