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					Fruits and Vegetables
• This stuff is scattered in the book.
    – Pp. 92-101
    – pp. 44-47

•   Tomato
•   Apple
•   Citrus
•   Brassica
•   Banana
•   Carrot
•   Onion
•   Squash and Melon
•   Tropical Fruits
     Fruits: Botanical and Popular
• Botanically, a fruit is the ripened ovary wall. The ovary is part of the
  carpel, the innermost whorl of a flower, the female reproductive
  structure. The ovary contains the ovules, the haploid equivalent to
  mammalian eggs.
    – Some fruits also contain parts of the flower base.
• Botanical fruits can be classified as fleshy, dry dehiscent, and dry
  indehiscent. Most of what are popularly called fruits are fleshy fruits.
• The generally understood common definition of a fruit is sweet and
  aromatic fleshy plant products that are mainly eaten as dessert or a first
  course in a meal, and not as the main meal.
• Thus, many fleshy fruits (in a botanical sense), such as tomato and
  cucumber, are considered vegetables in popular culture.
• In botany, a vegetable is simply any plant or plant part.
• In the common definition, vegetables are plant products eaten with the
  main course. In taste, they are salty or sour or savory, but not sweet.
  Some vegetables are botanical fruits: tomatoes and cucumbers for
  example. Others are plant stems, leaves, and roots.
                      Legal Fruits

• Botanically, a fruit is an ovary that has ripened after fertilization.
• However, in 1883 a 10% duty was placed on all vegetables being imported
  into the US.
• John Nix, an imported from New Jersey, argued that he shouldn’t have to
  pay the duty on tomatoes, because botanists consider them fruits.
• The case went all the way to the Supreme Court (which means at least 3
  separate courts examined the question). In 1893, the Court ruled that for
  legal purposes, tomatoes were a vegetable, not a fruit.
• Based on popular usage: vegetables (including tomatoes) are eaten at
  dinner, while fruits are sweet and are eaten at dessert.
• Tomatoes are the state vegetable of New Jersey. Ohio considers tomatoes
  to be the state fruit. In Arkansas, tomatoes are both the state vegetable and
  the state fruit (indecisive).
 Tomato Fight!

• In Spain, they
  have an annual
  tomato fight
• The tomato is a New World crop, native to the
  west coast of South America and first domesticated
  in Mexico. It is in the Solanaceae (nightshade)
  family, as are potato, chile pepper, tobacco, and
    – Species: Solanum lycopersicum, but until recently
      Lycopersicon esculentum.
• Brought back to Europe and to Asia (initially to
  the Phillipines) by the Spanish. It grew well in the
  Mediterranean climate and quickly caught on there.
• Many varieties. A big distinction: determinate vs.
    – Determinate tomatoes flower and set fruit all at once, and
      have a sfixedsize. Bush tomatoes, favored by commercial
    – Indeterminate varieties are vine types, which contnue to
      flower and set fruit until killed by a frost. Favored by
      home growers.
                                Tomato Stories
• Lycopersicon means “wolf peach”, because it is related to
  deadly nightshade. Some thought it could be used to generate
  werewolves: this was an old German legend about nightshade,
  which Linnaeus borrowed when he named the species.
• It was thought to be poisonous in Britain and America, despite
  being eaten in large quantities elsewhere.
    – In 1820, Colonel Robert Gibbon Johnson stood on the steps of the Salem
      Massachusetts courthouse, in front of 2000 people, and ate an entire
      bushel of tomatoes to prove that they weren’t poisonous. He survived.
      The local band played a mournful dirge as he ate, because they were sure
      he would soon die.
    – This story may not actually be true: the first account appeared in print in
      1906. It was dramatized in an early television series called “You Are
      There”, in 1949.
• First varieties to reach Europe were yellow, not red. In Italy
  they were called pomo d’oro (golden apple). This may have
  been mistranslated into French as pommes d’amour (love
    – Some thought they were aphrodisiacs (one of the eternal quests of
                     Tomato Pollination
• The wild plants are self-incompatible: they
  must be outcrossed to produce seeds and fruit.
    – To facilitate this, the female parts extend well
      beyond the flower, and the stamens stay enclosed
      within the petals.
• The native pollinator, a small bee, didn’t
  move with the plants to the Old World.
• Selection for self-fertility was very useful.
  However, the anthers shed pollen very slowly,
  and is aided by the wind or the wing motion
  of bumblebees. In the greenhouse, a vibrator
  is used (the “electric bee”). This is called buzz
  pollination. The bumble bees want to eat the
  pollen: tomato flowers produce very little
                         Growing Tomatoes
• Tomatoes are often picked green (unripe), because
  they are firm and survive mechanical harvesting and
  shipping better.
    – Much plant breeding work went into producing fruit that
      could be harvested mechanically. One result was the
      “square tomato”.
• They can be ripened with ethylene gas.
    – Ethylene is a plant hormone that stimulates flower
      opening, fruit ripening, and leaf shedding in many
      plants. It has been used since ancient Egyptian times
      to stimulate fruit ripening, by burning incense or by
      gashing figs in a closed room. A modern use it to put
      unripe fruit in a closed paper bag with a banana,
      which concentrates the ethylene the banana produces
      and speeds ripening. It is produced by almost all
      plants, both as part of the natural fruiting cycle and in
      response to wounding or other stresses.
    – Conversely, florists use ethylene inhibitors to extend
      the shelf life of cut flowers.
                Flavr-Savr Tomatoes
• The Flavr-Savr tomato was the first
  genetically engineered food product allowed
  on the US market, starting in 1994.
    – It was more resistant to spoiling and rotting, it had a
      longer shelf life, than normal tomatoes.
    – This was accomplished by blocking the enzyme
      polygalacturonidase, which degrades the cell walls
      and makes fruit more susceptible to fungal infection
      (which is what rotting is).
• Didn’t catch on. A big problem was that the
  starting tomatoes were not from a high quality
  strain, so yield was less than half of what
  good commercial varieties produce, and many
  of the fruits were small. Also, the fruits were
  more delicate than regular tomatoes.
• Production ceased in 1997.
• Apple trees (Malus pumila) are native to central Asia. The capital city
  of Kazakhstan, Alma-Ata, means “father of the apple”. (The city is
  now named Almaty).
• Alexander the Great brought them back to Europe in 300 BC.
• Apples are members of the Rosaceae, the rose family. Many other
  fruits also come from three subdivisions of this family:
    – The apple subfamily also includes pears and quinces. The fruits are
      called pomes.
    – The plum subfamily includes plums, cherries, apricots, and peaches:
      “stone fruit”, also called drupes.
    – The rose subfamily includes strawberry, raspberry, and blackberry.
      These are aggregate fruits: several ovaries fused together.
• Apples account for 60% of the temperate region’s fruit production. It
  is the world’s second largest fruit crop, after oranges.
                          Growing Apples
•   Apples can be grown from seeds, that is, by sexual
    reproduction. However, apples are genetically diverse, and
    the process of meiosis ensures that every seed will be
    different from all others. This diversity is good for survival
    in nature, but it is bad for agriculture: there is no easy way to
    maintain specific varieties if the plants are grown from seed.
•   Genetic uniformity is achieved by growing them
    vegetatively, by grafting cuttings onto the base of other trees.
    The base tree, called the rootstock, is from a strain that is
    disease-resistant and grows well in the region, but doesn’t
    produce high quality fruits. The scion (the grafted plant),
    produces good fruits of a specific variety.
•   When new varieties are desired, the trees are grown from
    seed. Most new varieties appear spontaneously among the
    offspring of genetic crosses between different strains.
    Sometimes “bud sports” appear: mutations that occurred in a
    bid, producing a branch on a tree that it noticeably different
    from the rest of the tree.
      Apple Flower and Fruit
• To produce fruits, apple flowers must be
  pollinated, usually by honeybees.
• The apple fruit consists of an ovary with 5
  carpels fused together, surrounded by
  “accessory tissue”. The accessory tissue
  develops from the receptacle, the place where
  the flower is inserted into the plant stem.
    – The swollen ovary containing the seeds is the
      core, and it is separated from the accessory
      tissue by a thin brown line.
• Most apples are picked by hand, either directly
  by the consumers or by low paid migrant
• Mechanical harvesters are often used for cider
  apples: still not well developed.
             A Few Apple Legends
•   Adam and Eve, the first man and woman in the Bible. The Devil
    tempted Eve to eat the fruit of the Tree of Knowledge of Good and
    Evil, which God had forbidden. She then convinced Adam to eat it
    also. For this action, God tossed them out of the Garden of Eden and
    forced them and all their descendants to work for a living. But, this
    fruit may have actually been an apricot: it is not clear that apples grew
    anywhere near the Middle East when the Bible was written.
•   William Tell, the Swiss hero and crossbow expert, refused to bow to
    the hat of the Austrian overlord (Gessler), which had been set on a pole
    in the town square. For this crime, he was forced to shoot an apple off
    his son’s head. When Gessler asked why he had taken out two
    crossbow bolts, Tell replied that if he had missed with the first one, the
    second arrow was meant for Gessler himself. This sparked a rebellion
    that led to Switzerland becoming free of the Austrian Empire in 1315.
•   Isaac Newton supposedly “discovered” gravity, or at least had the
    insight that gravity attracted the Moon towards the Earth in the same
    way that it attracted the apple toward the Earth, when an apple fell on
    his head.
•   And: New York City is “the Big Apple”, the Beatles’ record company
    Apple Corps, and the Apple computer company.
                       Johnny Appleseed
•   Johnny Appleseed. = John Chapman (1774-1845). He spread
    apples to western Pennsylvania, Indiana and Ohio.
     – He wore old ragged clothes, a pot on his head, and went barefoot
       most of the time. He was a vegetarian who was uncomfortable with
       romance, and he never settled down. Well-liked by all, a strong
       believer in the Swedenborg version of Christianity.
•   At that time, this area was part of the Old Northwest Territory,
    land west of the Appalachian Mountains, only lightly settled by
     – It had been French territory, but was ceded to Britain in 1763.
     – The British forbade European settlement west of the Appalachians.
     – After the American Revolution, settlement began, despite armed
       resistance from the Native Americans. Resistance east of the
       Mississippi River ended in 1832, with the Blackhawk War in this
       part of Illinois. Abraham Lincoln participated.
•   Johnny Appleseed had a business: he planted apple nurseries
    from seeds, then left a local resident in charge. After the trees
    grew, they were sold to the settlers.
     – Apples were not well adapted to life in America, so using seeds
       instead of grafts aided in finding workable varieties.
• The apples planted by Johnny Appleseed were mostly used to
  make cider. We call this stuff hard cider today.
• Cider is made by grinding ripe apples, then pressing out the
  juice. The juice is allowed to ferment for up to 3 months.
    – During this time period, cider was a common beverage, since
      water was generally contaminated.
    – Fermentation stops when the alcohol content reaches about
      10%: this kills the yeast.
• The alcohol in cider can be concentrated to make applejack.
  The pioneer method is freeze-distillation. The cider was
  simply left out in winter weather. Some of the water would
  freeze, as pure water ice, leaving the alcohol still liquid. The
  colder the weather, the stronger the cider.
• During Prohibition (1930’s), alcohol as illegal, and “cider”
  got re-defined as unfermented , unclarified apple juice .
  Sometimes called soft cider.
• The citrus family (Rutaceae) contains many
  edible fruits: orange, grapefruit, tangerine, lemon,
  lime, and several other less well known species.
    – Not really clear how many species there are: lots of
      hybrids, both ancient and modern. And, some
      "species" are clonally propagated and not sexually
• The family is native to tropical southeast Asia.
  Most varieties are very sensitive to frost and can
  only be grown where it never freezes.
• Citrus flowers each have several carpels, and the
  fruits have a thick rind that surrounds a set of
  segments, each derived from a single carpel. The
  segments are filled with pulp.
                    Citrus History
• The citron was widely grown in the Mediterranean region in Greek and
  Roman times.
• Sour oranges, lemons, and limes were introduced by Arab traders in
  the Middle Ages.
• The sweet orange, today the world’s leading fruit crop, was brought to
  Europe by Portuguese traders in the 1500’s.
• Citrus came to the New World with the Spanish.
• Florida oranges are mostly grown for orange juice.
• Navel oranges came from Brazil, but all US navel oranges are
  probably descended from two trees planted in Riverside California in
                           Citrus Fruit
• Orange trees take 3 years to mature, and then bear fruit
  for about 20 years.
• Citrus fruits have a thick rind that contains oil glands.
  The glands secrete a fragrant essential oil, which
  attracts animals.
• The fruits have several fused carpels: each orange slice
  is derived from a single carpel.
• The fruits only ripen while on the tree, so they have to
  be picked when ripe, but not over-ripe.
• Oranges on the tree are a mottled yellow and green
  color. The orange color is due to carotene, which is
  masked by chlorophyll in the fruit. Ethylene gas can
  be used to speed up the degradation of the chlorophyll,
  leading to the orange color.
• Citrus fruits are high in vitamin C, which prevents
•   Scurvy is a disease caused by a vitamin C deficiency. Vitamin
    C is needed to help synthesize collagen, the main protein in our
    skin and connective tissue.
•   A person with scurvy becomes weak and listless, spots form on
    the skin, and the mucus membranes bleed. In bad cases, old
    wounds open up and the teeth fall out. If not treated, it is lethal.
•   Scurvy used to be very common on long sea voyages. Vitamin
    C is found in fruits, vegetables, and fresh meat, but all of these
    were lacking. Sailors ate salted meat and hard biscuits.
•   Most animals, but not primates (or guinea pigs) can synthesize
    their own vitamin C.
•   James Lind, a surgeon in the British navy, described how citrus
    fruits could prevent and cure scurvy in 1753. His ideas weren't
    consistently followed until the early 1900's.
     – British sailors are called "limey" because they were forced to eat
       limes to prevent scurvy.
•   Work with guinea pigs starting in 1907 led to the understanding
    that a specific nutrient was lacking, and eventually to the
    isolation of vitamin C and an understanding of how it works.
                         Orange Juice
• Most Florida oranges are converted into juice.
• Most fruit is hand picked. But mechanical harvesters are
  improving. One method is to shake the tree hard enough to
  knock all the fruit off.
• The ripe oranges are squeezed to extract the juice. Then,
  pulp and seeds are filtered out: most of this ends up as
  animal feed. The juice is then concentrated by evaporation,
  then frozen. It is now "frozen concentrated orange juice". It
  gets shipped to packaging plants around the country, often
  dairies, since the packaging process is the same as for milk.
  It gets reconstituted by adding water, then sold to the
• Some pulp is added back to produce the pulpy varieties
  favored by some consumers.
• Frozen concentrated orange juice is a commodity whose
  futures (bets on future costs) are traded publicly.
• The Brassica genus is part of the mustard family. A wide
  variety of vegetable crops come from Brassica: they are called
  cole crops. The condiment mustard also comes from members
  of this genus.
• Members of Brassica oleracea include: cabbage, collard greens,
  kale, Brussels sprouts, kohlrabi, broccoli, and cauliflower. The
  different strains have been bred for different traits.
• Also, B. chinensis is bok-choi, B. campestris is turnip, and
  rutabaga is B. rapa.
• Also, B. napus is rapeseed or canola, B. nigra is black mustard,
  B. alba is white mustard, and B. juncea is brown mustard.
    – The yellow color of prepared mustard (called American mustard in
      other countries) is due to tumeric added to the ground mustard
    – The hot taste of mustard is due to an enzyme reaction, which
      produces a volatile oil when the ground seeds are mixed with
                        Brassica Plants
• Brassica oleracea is native to the Atlantic coast of
  Europe, and was domesticated in ancient Greece. It is a
  cool weather crop.
• Mustard flowers are yellow or white, and they have 4
• The plants grow as a rosette of leaves that stays low to the
  ground. When it is mature, the plant "bolts". It shoots up
  a tall stem with the flowers on it.
    – Most of the Brassica vegetable crops are harvested before
      bolting. The expression "gone to seed", meaning decreased
      in quality because of age and neglect, comes from this
• Although most Brassica vegetables are eaten fresh,
  cabbage can be converted to sauerkraut by shredding it
  and allowing it to ferment in salt water. Sauerkraut can be
  stored for a long time, and it retains vitamin C.
    Brassica Breeding
•   The different varieties come from breeding for different traits.
•   Cabbage has lateral branches and meristems suppressed, so all
    growth goes into leaves produced by the terminal meristem.
•   Brussels sprouts are similar to cabbage, except each lateral
    meristem develops into a little head.
•   Kohlrabi is swollen stem bases.
•   Broccoli heads are immature flower buds
•   Cauliflower is a mass of stem tips, harvested before the flowers
    develop. The white color is due to a mutation that inhibits
                          Triangle of U
• Brassica species easily hybridize, and there
  is a set of tetraploid species derived from
  hybridization of diploids followed by
  doubling the chromosomes.
    – Chromosome numbers reflect the ancestral
• First noticed by Woo Jang-choon, a Korean
  working in Japan, in 1934. By the time his
  name had gone from Korean to Japanese to
  English, it came out Nagaharu U.
• Carving faces in turnips is (allegedly) an old tradition
  in the British Isles. Pumpkin carving is more recent
  (pumpkins are a New World crop).
• An Irish legend, with many variants explains the
  origin: Jack was a farmer who met up with the Devil
  one day. Jack managed to trap Satan in his wallet by
  putting a cross in there (the Devil lost his powers when
  faced with a cross). He let Old Scratch out only when
  he promised to never take Jack's soul. One day Jack
  died, and Heaven refused him: he hadn't been a very
  good person. And, due to his bargain, Hell also
  refused him. Jack was forced to wander for eternity in
  the darkness. But, the Devil, having a sense of humor,
  tossed him an ember from Hell, which never goes out.
  Jack hollowed out a turnip, his favorite vegetable, and
  put the ember in there to use as a lantern. He then
  wandered the Earth endlessly, and he became know as
  Jack of the Lantern, or Jack-o'-lantern.
• Genus Musa, several species. All edible bananas are
  lumped together as Musa x paradisiaca, which reflects
  their hybrid origin.
• Two forms are popular: the sweet banana we eat as a
  fruit, and the starchy plantain, which is cooked and eaten
  as a vegetable in many tropical countries.
    – In Asia, they are also used for beer making, and in general are
      used about like we use potatoes. Also, fiber for cloth and paper
      can be extracted.
• Native to Southeast Asia and northern Australia. The
  wild banana was very important in pre-agricultural days.
  Probably first domesticated in New Guinea
• Spread to India by 600 BC, and throughout the Pacific
  Ocean region by the Polynesians. Arab traders brought
  it to Africa about 2000 years ago. It flourished and
  spread throughout the Old World tropics.
• Brought to the New World by the Portuguese in the
  1500’s. Did well here too.
             Bananas as Plants
• The banana is a monocot, and the trunk of the banana tree
  is really tightly packed leaf bases arising from an
  underground corm.
• The plant takes about a year to mature, starting from a
  cutting. It then flowers and sets fruit. The plant then dies,
  but the corm send out new stems (called suckers).
• Fruits are picked green (unripe). Ripening is induced are
  they have been shipped to market, by treating them with
  ethylene gas.
• Most varieties are sterile triploids, which are propagated
  vegetatively. They are seedless for this reason.
    – Also leaves them vulnerable to pathogens: bananas are genetically
      identical, so a pathogen that kills one will probably be able to kill all
      of them. The banana industry is periodically devastated by such
      diseases, and much breeding work goes into developing resistant
                               Seedless Fruit
• Banana fruits develop without fertilization. This is
  called parthenocarpy, and it is a common way of getting
  seedless fruit. It is due to a spontaneous genetic
  mutation, and it is found naturally in many plants.
• When a plant is moved from its ancestral home to
  another part of the world, the pollinating insect (or bird,
  etc.) often doesn’t came along or can’t survive.
• A variation on parthenocarpy: some fruits need
  fertilization to develop, even though the embryos abort.
  Thus the seeds are tiny or non-existent.
• In some species, spraying with plant hormones like
  auxin can induce parthenocarpy. This is commonly
  done with garden tomatoes.
    – This can also be done with genetic engineering.
• Triploids are naturally sterile and seedless. Triploids
  can be propagated vegetatively, or triploid seeds can be
  produced by crossing a diploid with a tetraploid.
                      Banana Republics
• Bananas rot quickly after harvest. Before steam ships,
  they were almost unknown in temperate climates.
• Around 1900, refrigerated steam ships were able to
  bring them to market in America and Europe. This
  led to a vast increase in their popularity. At one point,
  bananas were cheaper than local-grown apples!
• The United Fruit Company owned much of the land
  and infrastructure in several Central American
  countries, including Nicaragua, Honduras, Guatemala,
  Panama, and El Salvador.
    – The people who had formerly farmed the land were then hired
      at extremely low wages to work the plantations.
• Several violent coups were engineered by United Fruit
  to remove popular governments that wanted to
  interfere. Vastly unequal distribution of wealth and
  political problems remain as a legacy in Central
  America to the present time.
•   Daucus carota. Domesticated form of Queen Anne's Lace, a
    common roadside flower in late summer.
     – Umbel-shaped flower.
•   Contains carotene, the orange pigment which the body converts
    to vitamin A (retinol), the visual pigment.
     – The idea that eating a lot of carrots will improve your night vision
       started in England in World War 2, when British gunners were
       able to accurately shoot down German airplanes in the dark of
       night. This was actually because the British had invented radar,
       but they didn't want the Germans to know that, so the British
       government propaganda ministry started the rumor about carrots.
•   biennial: grow as a low rosette of leaves one year, store food in
    underground taproot (which we eat), then send up a flower stalk
    the next year using that food.
     – We harvest it after the first growing season.
•   Diploid, grown from seed. Commercial seed is inbred enough
    to give uniform growth, but not so inbred as to produce
    inbreeding depression.
•   Native to Afghanistan (it's the center of
    diversity). And other temperate parts of
    western Asia and eastern Europe.
•   In the wild, carrot roots are branched and
    woody: we have selected for a single
    unbranched taproot.
•   When first domesticated, carrots were
     – Caused by a pigment called anthocyanin,
       which is used in many flowers for red,
       pink, and purple shades. It's water
       soluble, producing purple-brown stews
     – Spontaneous mutants removed this
       pigment: same taste, but no ugly color in
       the stew.
          Other Carrot Family Crops
•   Carrots are members of the Apiaceae (also called
    Umbelliferaceae) family.
     – Aromatic plants with hollow stems, feathery leaves, and flowers
       like umbrellas.
     – The flowers attract parasitic wasps, which kill garden insects.
       This makes carrots good companions for other garden plants.
•   We also eat parsnips, which look a lot like white carrots.
    And celery is also a member of this family.
•   Many aromatic herbs: parsley, dill, coriander, cilantro,
    cumin, fennel, caraway (seeds in rye bread), anise (licorice
     – Coriander is the seeds and cilantro the leaves of the same plant.
•   Some are quite poisonous. For example, hemlock, which
    Socrates was forced to drink for his execution for corrupting
    the morals of the young. Hemlock grows wild here in
•   Silphium, a giant member of this family, was used for birth
    control in ancient Roman Empire. It is now extinct. Grew
    only in a small region of the Mediterranean coast in Libya,
    and it was over-used.
•   Allium cepa.
•   Onions are in the Lily family, which is a monocot.
•   Onion is really a biennial or perennial: the bulb grows in one
    year, then it sends up a flower stalk in the next year. We harvest
    them after the first season.

•   We eat the bulb: underground stem base surrounded by fleshy
•   In former times it was used as medicine for a large number of
•   Smell due to release of smelly sulfur compound
•   Tears when cutting come from release of sulfuric acid and related

•   Can be grown from seed or from seed sets, which are small
    onions grown from seed: using a seed set gives them a head start
    so they get bigger during the growing season.
•   Wild onions are edible: it was probably harvested from the
    wild long before it was cultivated.
•   Cultivated from early times in both Egypt and China by 3000
    BC. It stores well.
•   Wild relatives in Central Asia, so that's probably where it
    was first domesticated, but no direct proof of this.
•   We tend to use onion as a food flavoring, but it can also be
    eaten as a vegetable
     – unattributed odd "fact": the people who built in Pyramids in
       Egypt may have lived on radishes and onions. Wikipedia links
       to a food/garden site that just says it out of the blue.

•   Onion (as Allium) is a garden flower: blue puffball heads.
    It's a perennial.

•   Other relatives: garlic, leek, shallot, chives.
     – Garlic usage has greatly increased in the US in recent years:
       people like spicier food.
                     Squashes and Melons
•   Both are members of the Curcurbitaceae, the
    cucumber family. Squashes domesticated in New
    World, melons in Old World: Africa and South East
    Asia independently. Very early domestication.
•   All are creeping vines with separate male and female
    flowers on the same plant. We eat the fruits, which
    have multiple seeds surrounded by a fleshy fruit that
    has a hard rind.
•   Originally grown for the seeds: wild relatives can be
    eaten but the flesh is bitter. Seeds high in sulfur-
    containing amino acids. Pumpkin seeds are still
    widely eaten.
•   Hard rind makes them easy to store, and soft flesh
    works well as a water source in the desert.
• Squash: four cultivated species in the genus
  Curcurbita, with lots of variation in form
  within each species, and overlapping
  between species. E.g., "winter squash" and
  "pumpkin" can be any one of the four.
• Types: pumpkins, zucchini, butternut,
  turban, acorn, summer, plus others.
• Squash was gown along with maize and
  beans in ancient Mexico. The vine provides
  a ground cover that suppresses weeds, the
  beans fertilize the soil by fixing nitrogen,
  and the maize provides a living pole for the
  beans to grow on. This is called the “three
  sisters” method.
• Giant pumpkins are Curcurbita maxima.
  Current record (2010): 1810.5 pounds. It’s
  been going up by 50 pounds a year or so.
•   Watermelon are from west Africa. Eaten in ancient
    Egypt by 2000 BC. King Tutankhamen's tomb contained
    many watermelon seeds. Grown in China by 1000 AD.
•   Cantaloupe and honeydew melons are from central Asia.
    Also cucumbers: same species.
•   Cucumbers can be turned into pickles by soaking them in
    salt water (brine) at low pH (acid). Sometimes vinegar is
    added, along with spices such as dill and garlic. A
    bacterial fermentation process turns them sour.
    Originally used for food preservation, now mostly for
    flavor. Other vegetables can be pickled.
     – Playwright Neil Simon once said, “Words with a k in it are
       funny. Alka-Seltzer is funny. Chicken is funny. Pickle is
•   Loofah is a species of curcurbit whose fruit is allowed to
    partially rot, leaving a network of fibrous tissue. This is
    used for scrubbing your body: the loofah sponge. The
    fruit can also be eaten as a vegetable before it matures.
• The calabash, or bottle gourd, is another curcurbit of
  note. It was one of the first domesticated plants.
• It is grown for use as a container, not for food. When
  dried out, the woody rind in strong and waterproof.
    – Also used as a body for musical instruments,: stringed,
      rattles and drums
    – and often highly decorated.
    – It also has been used for smoking pipe bowls: Sherlock
      Holmes (a fictional character) smoked a calabash pipe.
                     Calabash Origins
• The calabash originated in the dry warm areas of southern Africa, where
  there a wild relatives.
    – The wild species have thin rinds: the cultivated varieties have clearly been
      selected for thick waterproof rinds.
• However, the calabash reached Asia very early: it has been found at
  archeological sites that are 8000 years old.
    – Today Asian and African varieties are relatively distinct.
• The calabash was also grown in the New World 8000 years ago, long before
  Columbus. This leads to. another ancient contact story: how did it get to the
• The main theory for the past 150 years: it rafted across the Atlantic Ocean
  from Africa in a mass of vegetation without human assistance. The rind is
  quite waterproof and the seeds are capable of germinating after a long
  dormancy period.
    – Alternative: a boatload of African fishermen blown off course and landing in
      South America.
    – Much less likely: by boat across the Pacific Ocean. Polynesia was settled much
      later: between 3000 and 1000 years ago.
More Calabash Origins
• Recent genetic and archeological study shows
  that the pre-Columbian calabash in America
  came from Asia. (D.L. Erickson et al., 2005, Proc.
    Nat. Acad. Sci USA 102:18315-18320)
      – This suggests it came over the Bering Land
        Bridge around 12,000 years ago with the
        original inhabitants of the New World, the
        Paleoindians. Sea level was much lower at that
        time, due to the Ice Age glaciers locking up
        much water.
      – They were hunter-gatherers: settled agriculture
        hadn’t been invented yet. They also brought the
        dog to the New World.
•   Dates from carbon-14 decay. It gets into plants
    from carbon dioxide in the atmosphere. When the
    plant dies, no new C-14 is added, and it slowly
    decays into nitrogen. So, the amount of C-14 left is
    proportional to how long ago the plant died.
     – Calibrated by counting tree rings. In some places, tree
       ring chronologies go back 10,000 years.
                       Genetic Evidence
•   The scientists involved here wanted to compare DNA from New World
    archeological specimens to plants grown today in Africa and Asia.
     – They collected calabashes from traditional farmers in both Africa and Asia, to avoid
       getting seeds form modern cultivars.
•   Also needed very careful treatment of archeological material to avoid
    contaminating ancient DNA with modern DNA.
•   Looking for differences in the DNA that would reliably distinguish between Asian
    and African varieties. There are a few regions in the genome that are easy to
    analyze and known to be quite variable. Mostly, the Asian and African varieties
    proved to be very similar in their DNA.
     – Found three good differences in the chloroplast DNA. All modern Asian varieties had
       one allele and all modern African varieties had the other allele.
•   Results: of the 12 archeological samples, only 10 produced any data. Of these, the
    nine that had pre-Columbian dates all had the Asian DNA markers.
     – The one with a post-Columbian date had the African markers: Columbus brought the
       African variety to the New World, and it has mostly replaced the Asian variety.
•   So, there is strong evidence that the pre-Columbian calabash came from Asia.
    How it got there is not proven: the Bering Land Bridge theory fits well with other
    knowledge of how the New World was settled.
Calabash Data
            Tropical Fruits
• Pineapple, date, figs, coconut, avocado,
  pomegranate, mango, papaya.
• Plus lots of others that are very tasty but
  don't ship well, so are only eaten locally.
• Not to mention nuts, which we haven't even
  touched on.
• The mind boggles…