Sunday, November 19, 2017

Plant Story--Perplexing Pumpkins

We have no problem recognizing pumpkins


and yet, botanically they're difficult.

Four plant species are "pumpkins": Cucurbita moscata, Cucurbita argyrosperma, C. maxima and Cucurbita pepo.

That would not be particularly confusing, except that those same plant species also give us summer and winter squashes. Thus, different varieties of Cucurbita pepo, for example, are acorn squash, zucchini and sugar pumpkins.

Squashes at a farmer's market
How do you recognize a pumpkin? Well, actually, a pumpkin is a winter squash. Which winter squash?  One that people determined is a pumpkin. Generally that means a large fruit with ridges. But as noted above, it can be any of four different squash species and at the same time it will have closer relatives that are not pumpkins.

The distinction between winter squash and summer squash is whether the fruit was harvested ripe or not. Winter squashes are the ripe fruits with hard exteriors and mature seeds inside, summer squashes are immature fruits, the seeds not fully developed, the outside soft. Pumpkins are winter squashes that people call pumpkins.

I can explain how it got that way, but not simplify the current situation.

In short: "people did it!"

Thousands of years ago, 14 species of wild squash, genus Cucurbita, grew in the Americas, from what are now the Mid-Atlantic States through the tropics to temperate climates in Chile and Argentina. The fruits attracted humans and all across the Americas, they were gathered, then as agriculture evolved, domesticated. Cucurbita pepo, in particular, was the earliest plant cultivated in the Americas, in Mexico some 10,000 years ago and independently just a little later, in the southeastern U.S. South of where C. pepo grows, other people gathered and then domesticated C. argyrosperma (southern Mexico), C. moschata (northern South America), C. ficifolia (northern Chle) and C. maxima (central Chile/Argentina). All of this before 5,000 years ago.

One of the outcomes of ancient squash domestication is that the fruits of our cultivated squashes are the most increased in size from their wild ancestors of any crop plant. Look at this photo of a wild Cucurbita pepo collected in 1967 in the Illinois State Museum herbarium link The fruit is smaller than the leaves. (The page it is glued on is 11.5" by 16.5"). From wild ancestors like this came pumpkins, including giant ones. See photos of record pumpkins link.

All my pumpkins photos are this same species Cucurbita pepo. Pumpkins of other Cucurbita species are harder to find--though I'm planning to grow them next summer to see what they look like. Seeds of pumpkins of other species are available from online from sources such as Johnny's Selected Seeds link and Baker Creek Heirloom Seeds link, both of whom give scientific names.


Over five millennia of cultivation, people shaped the squashes, creating varieties that are green, orange, yellow, and brown, round, oval, and crook-necked, tiny and huge. In the processes, people in the different regions sometimes produced fruits that looked very similar to those from other species.

Then, 500 years ago, Europeans arrived. Eurasia has melons and gourds (Citrullus, Cucumis, Luffa) but not squashes. Europeans immediately appreciated the squashes they found. They packed them onto their sailing ships and took them around the world, not only back to Europe, but to Africa, to India, to southeast Asia and the Philippines, and to China and Japan. All over the world people embraced the squashes and over the last 500 years, bred them for characteristics they liked, making even more varieties.

But notice, the Europeans didn't just take plants from Mexico. Plants from Massachusetts, Virginia, Guatemala, Brazil, Peru and Chile, and more, went worldwide. As a rule the species of Cucurbita do not cross, so they didn't produce a hybrid swarm in those exotic gardens. What did cross were the different varieties of the same species, making zuccini-pumpkins or acorn squash-pumpkins. Consequently more varieties were produced, so that as you step into the vegetable section of the market today, you are confronted with wonderful squash diversity, labled variously as butternut, hubbard, zenith, ponca, patty pan, pumpkin and more.


For squashes, the key is whether they are soft-skinned summer squashes or hard-rind winter squashes, even though they may botanically be any of five different Cucurbita species. But the pumpkins? I find no simple definition of pumpkin. It is a winter squash that you or the seller calls a pumpkin. Ridges are usual. Orange color is common. But see the diversity at, for example, link.

ghost pumpkins
ghost pumpkins
The name pumpkin is borrowed from a melon or gourd. You can find the word in French writing before Columbus: pompion and pompon. The English versions, pompion and pumpkin, were applied to big fruits related to melons and squashes but since the Oxford English Dictionary has no records of those words before 1500 whether the quotes apply to a melon or a squash is unclear. I admit, only a botanist would care. And clearly after somebody applied the old name to a big winter squash, it stuck. Today the word pompion is obsolete and big orange winter squashes with ridges are pumpkins.

English had another now-obscure word for melons, pepon, based on the Latin word for a watermelon or big gourd, but the Oxford English Dictionary treated this word as independent of pompion and pumpkin as English words, so did not think it the ancestor of the word pumpkin.

Pumpkins are diverse not just because of their diverse origins and human preferences, but because they are grown for different reasons. Specialized lines of pumpkins produce pumpkin seeds. Other pumpkins are raised as a vegetable used in soups and stews. Other pumpkins are cooked and sweetende for pies and other dessert. Particular pumpkins are best to carve into jack-o-lanterns or grow very large in pumpkin-growing competitions. There are better and worse pumpkins for each of these uses. When you imagine shoppers in Japan and India choosing pumpkins, as well as those in Italy, Oregon and Georgia, it is clear that different climates. uses and buyer preferences continue to drive pumpkin diversification.

For me, this is how a pumpkin looks!
Celebrate pumpkins!

Comments and corrections welcome.

History of pumpkins at link
Oxford English Dictionary online: pumpkin n., pompion n., and pepon n., accessed Nov. 14 2017.
Kates, H. R., P. S. Soltis and D. E. Soltis. 2017. Evolutionary and domestication history of Cucurbita (pumpkin and squash) species inferred from 44 nuclear loci. Molecular Phylogenetics and Evolution. 111: 98-109.
Keeler, K. A Wandering Botanist: 2014. Plant Story--American Squashes link
Nesom, G. L. 2011. New state records for Citrullus, Cucumis and Cucurbita (Cucurbitaceae) outside of cultivation in the USA. Phytoneuron. 2011-1: 1-2.
Nosowitz, D. 2017. The Modern Farmer guide to winter squash varieties. Modern Farmer. (Nov. 2, 2017) online accessed Nov. 14, 2017.
van Wyk, B-E. 2005  Food plants of the world. Timber Press, Portland, OR.

Kathy Keeler, A Wandering Botanist
You can find similar stories in Curious Stories of Familiar Garden Plants , available from Amazon link

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