The cucurbit family includes plants that are among the most useful food plants domesticated and cultivated by humans.  This large family of inter-related species includes cucumbers, squash, citron, melons and hundreds of wild species, that are not cultivated by us for food.

The Cucurbitae are also known as the Gourd Family.  They are vining plants that produce flat seeds enclosed in a large fleshy body.   The family includes 975 species of food and ornamental plants, native to both temperate and tropical areas.  The Cucurbitae include cucumbers, gourds, melons, squashes and pumpkins. 

Most of these vines are sensitive to temperatures near the freezing point, which tends to limit their geographic distribution.  Most are fast-growing, prostrate plants or climbing vines.  They have long-stalked palmate leaves, that alternate along the stem.   Along the side, they send out a tendril that may be branched, and that curls around to find purchase and support the stem.

Most cucurbits have unisexual (male or female) flowers, so pollination depends on pollen making it from the male to the female flower.   This turns out to be a key to isolating varieties and keeping them from crossing.   The flowers have five white or yellow petals, and when pollinated they produce a “pepo,” a fleshy, many seeded large berry with a tough rind to protect the seeds and provide food for the seeds once germinated.   The large fleshy fruit may also offer protection from lower temperatures as these plants have worked their way north into colder climates.   Seeds are elliptical, flattened and may have wings for dispersal.

Some gardeners will be familiar with what happens when cucurbits cross.  For example, when pollen from a pumpkin reaches a female squash flower, the result can be a hybrid fruit that is neither.   Tales of squmpkins, gourdchinis and cuculoupes reveal that this can happen, if plants are growing too near each other or bees carry pollen between plants.   However, not all cucurbits can cross.

It helps to know that there are actually seven separate species of cucurbits.  Within each species, plants can cross-pollinate, but they will not do this across species boundaries. 

So what are the seven species of cucurbits and which food plants do they include?

Group A – Cucurbita pepo, which includes:

  • Summer Squash – Yellow crookneck, straight neck, zucchini, scallop and patty pan squash
  • Winter Squash – Acorn and spaghetti squash varieties
  • Gourds – the many ornamental non-edible types
  • Pumpkins – including the varieties known as Cinderella, Big Tom, Jack O’Lantern, Small Sugar,    Sugar Pie, Jackpot and Connecticut Field Pumpkins

Group B – Cucurbita moschata, which includes:

  • Winter Squash – Butternut squash
  • Pumkins – varieties known as Cheese, Dickinson Field, Golden Cushaw and Kentucky Field

Group C – Cucurbita maxima, which includes:

  • Winter Squash – Hubbard varieties
  • Pumkins – Big Max, King of the Mammoths, Mammoth Chile and Atlantic Giant
  • Ornamental Squash – Alladin and Turk’s Turban

Group D – Cucurbita mixta, which includes:

  • Pumpkins – Green-striped Cushaw, Japanese Pie, Tennessee “Sweet Potato”, White Cushaw              and Mixta Gold

Group E – Cucumis sativus, which includes:

  • Cucumbers – all common slicing and pickling cucumber, except the Armenian type
  • Beit Alpha Cucumber
  • Lemon Cucumber

Group F – Cucumis melo, which includes:

  • Cucumber – The Armenian “snake cucumber” also known as Serpent Melon
  • Melons – All the muskmelons, including cantaloupe, casaba and honeydew

Group G – Citrullus lanatus,  which includes:

  • Watermelons
  • Citrons

So if you are growing two squash or pumpkin or cucumber plants side by side they will not cross, or are very unlikely to cross, if they belong to different species.  If you do grow two plants in the same species then the key to getting the fruit you want is creating physical isolation: planting them more than one hundred feet apart.  In a small garden, this is not easy.

So growers eliminate the possibility of crossing by hand pollinating.  To do this, you will need to pluck a male flower and use it to dust female flowers on the same or nearby plants of the same species.   To make sure no crossing occurs, it is also advisable to put a paper bag around the female flower, once pollinated, until it wilts and the fruit begins to expand.  Then you can remove the bag, or just let it rot away, knowing the result will be true breeding.

Pumpkins, squash, cucumbers and their relatives are wonderful plants for ease of growing, the quantity of food they produce and their storability.   Whether you call it pumpkin or squash, the sweet meat from the large fruit can be cured in the sun, stored in a cool dry place (above freezing) and turned into delicious steamed vegetables, soups and pie fillings.

With pumpkins spread across four of the seven species it does help to know which varieties you are growing, if you want to keep them true-breeding and save seed for replanting.  And then there is the Atlantic Giant, those mammoth pumpkins developed originally in our region.  Grown competitively, they can top the scales at over a thousand pounds.  One of the secrets is to water them with soured milk and feed them lots of manure to get them that big.

But whether you are starting seeds for long English cucumbers or planning on pumpkins for your kids to carve at Halloween, knowing your cucurbits can help you sort out what to plant and where to grow it.   And when the flowers form, you get to be the pollen faerie, carrying dusty orange pollen from male to female flower.   With so many valuable members of the Cucurbitae on which we now depend for food, it’s clear that cucurbits and humans have a long standing relationship stretching back thousands of years.  We have been dancing this dance out in the pumpkin fields for a very long time!

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