Category Archives: Food

Sweet Potato Awareness Month

November is Sweet Potato Awareness Month (SPAM), and I do my part by reminding people that yams are something else entirely. As a foodie and an evolutionary biologist, I feel obliged to be a nudge about this. So here are three images to help.

First, a photograph of a white yam (Ipomoea rotunda) in a bin of sweet potatoes.

Colin Purrington Photography: Blog photos &emdash; A white yam (Dioscorea rotundata) in a bin of sweet potatoes (Ipomoea batatas)

Second, a photograph of three cultivars of sweet potato (all Ipomoea batatas) next to a yellow yam (Dioscorea cayennensis).

Photograph of sweet potatoes and yam

Third, an illustration of how yams and sweet potato are related (they aren’t). As a bonus, I’ve also indicated the position of potato.


Please share this page with your family prior to Thanksgiving dinner. It will be one less thing to bicker about. If you need more details, here’s my “Yams versus sweet potatoes” page. Read it if you want to know why the slave trade caused the whole “yam” confusion problem.

Posted in Biology, Education, Food, Gardening, Photography, Science | Tagged , , , , | Leave a comment

Distinguishing tobacco and tomato hornworm caterpillars

After agonizing over the identification of hornworm larvae for years, I’ve developed two tricks that I’d like to share. Tobacco hornworm (Manduca sexta) caterpillars have stripes (seven of them), so remember that by thinking of Lucky Strikes cigarettes. Horn is usually red or red-tipped, like a cigarette. Also, tobacco gives you dark teeth and lungs … and tobacco hornworms have black shadows on their stripes. Tomato hornworms (Manduca quinquemaculata) have eight chevrons (Vs), which you can remember by thinking of V8 juice, which is primarily tomato juice. Here’s the graphic you can share with friends who might have it wrong:

Photographs of tobacco and tomato hornworm caterpillars

If you can, please spread the word … most of the tens of thousands of tobacco hornworm photographs on the internet are misidentified as tomato hornworms. Even Wikipedia page for tomato hornworm shows tobacco hornworm larvae (I’m working on it …). The problem is that tobacco hornworm eats tomatoes, and people with fancy cameras grow a lot of tomatoes.

For people living in Hawaii, please note that the above doesn’t include Manduca blackburni, which is closely related to tomato hornworm.

Photograph of tomato hornworm from Amanda Hill.

Posted in Biology, Education, Food, Gardening, Photography, Science | Tagged , , , , , , , , , , , , , , | Leave a comment

Minor victory in my war against yam labeling fraud

In my futile quest to convince people that sweet potatoes shouldn’t be called yams (which are unrelated plants), I discovered that one can actually report vendors who label sweet potatoes as yams. So, for giggles, I reported Giant Foods to the USDA’s Misbranding and Misrepresentation Office. Below is a photograph I took in November of their organic sweet potatoes:

giant-sweet-potato-05 (1)

And now in all of their stores (that I’ve checked), they sell sweet potatoes labeled as sweet potatoes:

Nature's Promise sweet potato at Giant

It might be a small victory, but Giant Foods is giant, so I’m pleased. If you want to know more about my futile war, please see my page on Yams versus Sweet Potatoes. If you want to make your own report, just visit the above USDA site and send the contact person a photograph of the label along with store contact information. They’ll do the rest, and apparently in a persuasive way.

Posted in Biology, Education, Food, Gardening, Graphic design, Health, Photography, Science | Tagged , , , , , , , , , | 4 Comments

Teaching kids about sugar content of beverages

One out of three kids these days is overweight or obese, and consumption of drinks that have sugar is likely a big part of why, especially because some parents think such drinks are healthy. Sugar drinks also cause tooth decay (I know, big surprise there), and might even cause little kids to be aggressive. So I got to wondering what public schools are actually doing to educate kids about the sugar content of beverages. The answer: not a whole lot, at least from a cursory search of the internet.

So here’s the class activity I think all kindergarten classes should do: construct a poster for the hallway or classroom wall that visually displays how much sugar is hidden in common beverages. Here’s an example:

Sugar in drinksThis project would fit in perfectly with most state standards (for example, see page 10 in Health Education Content Standards for California Public Schools). And because it includes numbers (of teaspoons), teachers can use the poster content to visually drive discussions about addition and subtraction. If this poster was done in a fun way, the experience might vaccinate kids against over-consumption of sugary drinks for the remainder of their lives. The parallel to brushing teeth might be appropriate: you teach kids how to do it even though the chemistry of decay is beyond their understanding. If you don’t brush and floss, you’ll lose your teeth. That’s a lesson best taught when really young.

There are lots of ways to make the poster, but what I like about the one above is that water (no sugar) and plain milk (contains lactose … which is a sugar) are included. There should also be a sampling of common juices (apple, orange, e.g.) because they are loaded with sugar. And just for scale, it might be good to show how many teaspoons of sugar are in a typical bag of candy (e.g., Skittles).

Poster titles matter here, just like they do at a scientific meeting, in that they can provide a take-home message. “Rethink your drink” is a popular title (it rhymes), but I prefer something that confronts the point more directly. Here are some ideas: “Don’t drink dessert all day”, “Don’t drink your dessert”, or “Sugary drinks are candy drinks”. If snark is allowed in your district, then something like, “Sugary drinks are a sweet way to gain weight and rot teeth!” The idea is to be direct and memorable and to not shy away from the point: sugary drinks can (and do!) make kids fat.

If you want some background information relevant to lesson plans on sugar for K-3 levels, here are some resources from BrainPOP. If you’re looking for more examples of posters, here’s a Pinterest board where I collect them:

Pinterest board Educating kindergartners about sugary drinks on Pinterest.

Posted in Biology, Education, Food, Graphic design, Health, Photography, Science | Tagged , , , , , , , , , , , , , , , , , | 2 Comments