If you've been on Twitter during this holiday season, you might have caught wind of the #plantsgiving challenge: a friendly competition to see who can feature the most plant species on their Thanksgiving table. The record currently stands at 66 plant species in one meal (!).
The diversity of plants used for human food is dazzling--from wheat, apples, and carrots to thyme, bay leaves, and black pepper--but this variety scarcely compares to uncultivated diversity. Today, we give thanks not only for the plant species on our Thanksgiving tables, but also the evolutionary relatives of these species, particularly those found in California. Here are a few fun examples:

Despite being a staple of many Eurasian diets, potatoes originated from the Americas (the specimen on the left was collected from Bolivia!) and were spread widely in cultivation. The potatoes we eat are the species Solanum tuberosum. Interestingly, this plant genus, Solanum, is an enormous group of over 1500 species, including the species that give us tomatoes and eggplants. Outside of cultivation, Solanum species are widespread and often weedy. Take for example the California native shown above and to the right, Solanum americanum (American black nightshade). This species thrives in disturbed places and has become a frequent weed in tropical and subtropical places across the globe. Far from mild nature of the potatoes we eat, American black nightshade is, like many of its relatives, poisonous at certain times in its development, but don't let that stop you from dipping into the mashed potatoes! The poison found in nightshade plants, called solanine, doesn't reach dangerous levels in mature tubers (aka potatoes) of Solanum tuberosum.

Don't leave without dessert! The last genus for today includes the famous pumpkin. Whether for carving, artful decoration, pie, or lattes, the pumpkin is a staple of autumn festivities in the U.S. The pumpkin genus, Cucurbita, contains several species of gourds and melons, each with a distinctive fleshy fruit called a pepo. Fittingly, Cucurbita pepo is the species of pumpkin we generally consume during the fall season. (Cultivars of C. pepo are also responsible for zucchini, acorn squash, and summer squash, but let's leave the wonders of artificial selection to a future blog post.)

The specimen on the left is a pumpkin (C. pepo​) that escaped cultivation due to flooding, deemed a waif ​by the collector. On the right is an established California native, Cucurbita palmata, also known as coyote melon or coyote gourd. This species occurs in southern California, especially in hot, arid areas. As demonstrated above, C. palmata shares similar morphology and habit to the familiar pumpkin; its stiff-haired vines and tendrils crawl across the ground, and it produces coarse, hairy leaves and the distinctive pepo fruit. Unfortunately, coyote melon does not share the rich, tasty flavor of our beloved field pumpkins, but that doesn't stop a variety of moth species from feasting on the plant, despite its distasteful hairs.

What species do you find on your Thanksgiving table, and do these species have native relatives in your area? Answers to these questions and many more are aided by our knowledge of biodiversity from herbarium specimens.
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​Glossary

• genus - scientific name that denotes a rank above species but below family
• habit - the general architecture or form in which a plant grows (e.g., tree, shrub, vine)
• morphology - appearance and appearance-related traits (e.g., leaf shape, color)
• pepo - a type of fleshy fruit with a tough rind, produced by a species of the melon family
• tuber - an underground stem or rhizome that is enlarged and thickened, usually for storage of starch and minerals for the plant
• waif - plant occurring outside of its usual range or circumstances that is not likely to persist

What do the following specimens have in common?

Both were collected by U.S. veterans. In honor of Veterans Day, today we highlight two of the many influential botanists who served in the U.S. Armed Forces.

At the time when he collected the specimen on the left, Donovan Stewart Correll (1908-1983) was the head of the Botany Department of the Texas Research Foundation, where he and many collaborators authored the Manual of the Vascular Plants of Texas. Sixteen years earlier, however, his life had been much different. In 1943, he was exploring the cold, subarctic forests of Canada with the Alaska Military Highway Expedition. For two years afterward, he served as a gunnery officer for the U.S. Navy at the close of World War II. Don Correll never seemed to slow down--and neither did his wife, Dr. Helen B. Correll. The Drs. Correll  cataloged orchids of Guatemala, aquatic plants in the southeast U.S., and the magnificent tropical flora of the Bahama Archipelago.

The specimen on the right is only one of the over 30,000 collected by Reid Venable Moran (1916-2010), a world expert on the well-known succulent family, Crassulaceae. Moran enlisted in the U.S. Army Air Corps in 1942 and was promptly shot down over Yugoslavia--which gave him more time to do botany. After being rescued and while waiting in northern Africa to be shipped home, Moran collected African plants and visited the Botanical Garden and Laboratory at the University of Algiers. Like Correll, Moran was an active botanist and explorer for the rest of his life, making notable discoveries across Baja California and the many unique and threatened islands off the coast of California and Mexico. During his career, Moran worked at both the Santa Barbara Botanic Garden and the San Diego Natural History Museum, both of which are part of the California Phenology Network! Thousands of Moran's specimens--as well as many others--are being digitized through the California Phenology Network and made available online: cch2.org. His travels and those of thousands of other botanists are being preserved and disseminated through this digitization effort.

We are grateful for the service of these botanical leaders, both to science and to the United States.