Category: Botany

Smelling Feet or Smelly Feet?

3/7/2023

Dorothy Hinshaw Patent
Nature’s Animal Ambassador

Do your feet sometimes smell rotten? Do you wish you could toss out your shoes and start with a new pair? We make jokes about smelly feet, but smell and feet have a very different relationship among some insects.

Take butterflies. Have you ever watched a butterfly flit over a plant, gently touch its feet to a leaf, and then fly on to the next leaf? That butterfly isn’t being picky about where to land. It’s hunting for the right kind of leaf for laying its eggs. It’s “smelling” the leaf with its feet!

Actually, we need to qualify that statement a bit. Some writers will say the insect is “smelling” the leaf while others may write that it’s “tasting” the leaf. Smelling and tasting are forms of “chemoreception,” or sensing of chemicals. Smell usually refers to sensing from a distance while tasting generally means actually touching the nerve cells that sense a chemical.

We humans have cells in our noses that send messages to our brains about chemicals in the air. We call that our sense of smell. We have cells on our tongues that sense chemicals dissolved in liquid in our mouths. That’s taste.

That butterfly doesn’t have a nose, and its mouth is a long tube for sucking up nectar from flowers. Its chemoreceptors are elsewhere, like on its feet, around its mouth, and on its antennae. Most butterflies lay their eggs on the plants that the hatched caterpillars will eat. Some species are very specific about what plants their young can feed on. Take the postman butterfly, which lives in Central and South America. Its caterpillars can only survive on certain species of passionflower vines. Other species are poisonous to their offspring.

The female postman butterfly has dozens of special nerve cells on her feet called “gustatory sensilla.” Scientists think that when she touches gently down on a leaf, these cells can sense chemicals there that would be poisonous to her caterpillars. She avoids laying eggs on those leaves. But when she finds a plant that will nourish her young, she’ll alight and lay her eggs.

Now take your shoes off and move your feet around on the floor. The only nerve endings on your feet are ones that sense touch. But then, you don’t need to be able to smell the ground you walk on. Imagine how gross it would be if your feet could smell the insides of your socks and shoes—yuck!

In these photographs taken through a microscope, you can see the sensory sensilla (arrow) on the feet of the female butterfly on the right, which the male on the left doesn't have. From PLoS Genet. Jul 2013; 9(7): e1003620.

Above: Postman butterfly feeding Right: Female postman butterfly laying an egg. As you can see from these two photos, the postman butterfly can have a variety of color patterns. From Heliconius.org

A dog’s nose is 300 times more powerful than a human nose, so it’s no wonder that dogs use their incredibly advanced sense of smell to do some very important jobs. In Super Sniffers, Dorothy Hinshaw Patent explores the various ways specific dogs have put their super sniffing ability to use: from bedbug sniffers to explosive detectors to life-saving allergy detectors . . . and more. This dynamic photo-essay includes first-hand accounts from the people who work closely with these amazing dogs. For more information, click here.

Dorothy Hinshaw Patent is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.

MLA 8 Citation
Patent, Dorothy Hinshaw. "Smelling Feet or Smelly Feet?" Nonfiction Minute, iNK
Think Tank, 23 Jan. 2018, www.nonfictionminute.org/the-nonfiction-minute/
Smelling-Feet-or-Smelly-Feet.

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Amazing Maize

11/23/2022

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Dorothy Hinshaw Patent

Nature's Animal Ambassador

If I asked you what grain is the most harvested in the world, you’d probably answer either wheat or rice. But the answer is actually corn, more accurately called ‘maize.’ This nutritious crop that originated in Mexico feeds not only people but also animals around the world. We’re used to the wonderfully tender sweet corn harvested in late summer and early autumn, but most maize is actually field corn, more starchy than sweet and used as animal feed or to make cornmeal and flour.

For a long time, biologists puzzled about the origins of this important crop. There is no wild plant that looks anything like modern corn, which is actually a giant grass. The closest relative is a scrawny branching plant with hard dark seeds called teosinte. It seems a huge jump from teosinte to corn, yet geneticist George Beadle found in the 1930s that corn and teosinte have the same number of chromosomes and could be crossbred to produce hybrids. With the limited tools available at that time, Beadle deduced that only about five genes were involved in creating the differences between teosinte and corn.

Fast forward to modern times, when scientists can look directly at DNA and analyze every detail of its structure. We now know that Beadle came very close to the truth—about five regions in the DNA seem to control the major differences between teosinte and corn. For example, these two plants look so very different, yet just one single gene turns a branched plant into a single stalk, like a stalk of corn. Another single gene controls one of the most dramatic and certainly most important traits for farmers—the nature of the seeds and their stalk. In teosinte, each seed has a hard covering. Just one gene eliminates the hard covering and produces a stalk bearing exposed seeds, like an ear of corn.

Scientists now use maize as a perfect example of two major ways evolution happens. One way is through major sudden jumps, like the change from a branching plant to a single stalk. The other is the more gradual kind of change that has led to the thousands of different kinds of maize grown by farmers today. There are probably hundreds of varieties of sweet corn and thousands of varieties of field corn. Think about that the next time you bite into a nice crunchy taco made from a corn tortilla.

Here you can see the major differences between a teosinte plant and a corn plant. Credit:TeosinteCornUOR

Corn was a very important crop for homesteaders in the American West, used both to feed themselves as well as their animals. Read about it in Homesteading: Settling America's Heartland, revised and expanded edition, Mountain Press, 2013.

Dorothy Hinshaw Patent is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.

MLA 8 Citation
Patent, Dorothy Hinshaw. "Amazing Maize." Nonfiction Minute, iNK Think Tank, 8
June 2018, www.nonfictionminute.org/the-nonfiction-minute/Amazing-Maize.

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Flower Power

3/22/2022

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Alexandra Siy
Science through the lens

Do you know about the “birds and the bees?” If you don’t, don’t worry. You will learn soon enough.

            When it comes to flowers there’s nothing to hide. There’s just no way around it—flowers are sexy. Their colorful, curvy petals are soft as velvet and as fragrant as the most expensive perfumes. Their nectar is as sweet as…well, honey. Besides being pretty, flowers have power. Their pollen is packed with protein. No wonder the birds and the bees, and insects of many kinds, find them so irresistible.

            Pollen may be the perfect food for bees, but it is also the way plants get together. Think about it. Plants can’t walk, crawl, swim, or fly. So, how does boy meet girl?

            In order to reproduce, the pollen from the male has to have direct contact with the female (and I don’t mean texting). Pollen grains are carried on the legs of bees and in the beaks of birds, from one flower to another. A few grains become engaged, hitched, and literally stuck on the sticky female flower part called the stigma. Sugar from the stigma fuels the pollen grain to sprout a tube. This pollen tube grows downward through the female part called the pistil and into the chambers that contain tiny bubble shaped eggs. When the tip of the pollen tube finally reaches an egg chamber it releases a male sperm cell. The sperm and the egg unite, and a brand-new cell is formed. This is the beginning of a seed.

            Picture an apple. Before the apple was a fruit containing seeds, it was a very sexy flower. So the next time someone asks you if you know about the birds and the bees, tell them about flower power. They might be surprised how plants get together to make baby plants, which in scientific terms is an interesting example of the process called sexual reproduction.

Pollen is contained in the anthers, which are the six slipper shaped sacs at the end of the stamens. The female stigma is the rounded tip located at the top of the style. The pollen tube is a microscopic tube that grows through the style and into the ovary, which is hidden inside the base of this flower. Hanging down, at the lower right side of the photo are the remains of another flower. The petals and stamen have fallen off revealing the entire pistil: the stigma, style, and the ovary (green structure), which holds the eggs. Photo credit © Alexandra Siy

A bee feeds from a daisy, which is composed of many miniature tube shaped flowers growing together as a central disk. This family of flowers are the most numerous on earth. Photo credit: © Alexandra Siy

Colorful petals enclose the sexual parts of the flower. This close-up shows several of the male stamens growing from the center of the flower. Photo credit © Alexandra Siy

Why not watch some web-spinners do their thing with the help of this stunning and superlative book by Alexandra Siy? You can read more about it here.

Alexandra Siy is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.

MLA 8 Citation

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Dr Percy Julian: Forgotten Genius

2/4/2022

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Kerrie Logan Hollihan
Teaching the Power of Wonder

Dr. Percy Julian was my neighbor in Oak Park, Illinois. I didn’t know the family who lived in the pretty home surrounded by an iron fence. But I heard the story, that the house was firebombed after they had bought it back in 1951. The Julian's were African-Americans coming to a white community.

Later I learned more. Dr. Julian was someone who didn’t take no for an answer. He grew up in the segregated South going to black-only schools. He hoped to study plant chemistry, but no southern college would accept a Negro, so he moved on. He went to DePauw University in Indiana and helped pay tuition by waiting tables at a white fraternity. He graduated at the top of his class in 1920 and wanted to get his doctorate at Harvard. Harvard refused, because that would mean Julian could teach whites—and that was not allowed.

Julian moved on. He went to Austria to earn his doctorate, and in that lab he studied chemicals in plants, especially beans. Many excellent medicines came from plant chemicals, but extracting them was often costly.

Upon returning to DePauw to teach, Julian was able to synthesize a plant chemical called physostigmine. His discovery produced inexpensive medicine for patients with glaucoma, an eye disease causing blindness. But the Great Depression fell across America, and DePauw ran out of money to fund his research.

Julian moved on. A Chicago paint company hired Julian as the first African-American to head a research lab in American industry. Julian had to travel for his work, and motels refused him a bed. One year he slept in his car 32 times, sometimes in the dead of winter.

Julian and his coworkers developed inks and paper coatings, dog food and a product called Aero-Foam to extinguish fires on aircraft carriers. His team discovered many uses for soybeans, at that time viewed as food for cows and pigs. Most important, they synthesized “Substance S” from soybeans. This synthetic drug replaced wildly-expensive cortisone. Julian’s landmark achievement offered relief to kids suffering from the painful and disfiguring disease rheumatoid arthritis.

Percy Julian worked all his days, always moving on to make life better. He built his own research business, volunteered at church, played the piano, and loved his family. He became a quiet hero to many, including me. I’m writing a book about Dr. Julian, which I hope you’ll see in print. For now, visit this site.

This Percy Julian stamp was issued in 1993 to commemorate Black History Month.

Kerrie Hollihan has already written about one great scientist, Sir Isaac Newton. You can read more about this book here.
Kerrie Hollihan is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.

MLA 8 Citation
Hollihan, Kerrie Logan. "Dr Percy Julian: Forgotten Genius." Nonfiction Minute,
iNK Think Tank, 13 Feb. 2018, www.nonfictionminute.org/
the-nonfiction-minute/dr-Percy-Julian-Forgotten-Genius.

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Smelling Feet or Smelly Feet?

Amazing Maize

Flower Power

Dr Percy Julian: Forgotten Genius

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