#noting science

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Berries and Drupes and Pomes, Oh my! A Botanical Guide to True (and Untrue) Berries

Does a berry by any other name taste as sweet? Probably, since the majority of fruits that get lumped together under the term “berry” aren't actually berries, botanically speaking. So what, according to science, makes a true berry different from an untrue one? Let's start by stepping back for a second to consider how any fruit – berry or not – forms. Fruit Formation All fruits are the product of flower fertilization. The female reproductive organ of a flower is called an ovary; it holds one or more egg cell-producing ovules. When pollen (which contains plant sperm cells) lands on a flower's stigma (a part of the pistil), it triggers the development of one or more seeds inside the ovary, and a fruit begins to form. The ovary walls to grow into a soft, fleshy pericarp around the seeds, which forms the outer layer of a fruit. In fact, you will find that you know many botanically-labelled fruits as vegetables; when scientists create classifications, they are only concerned with structure, and not with whether you'd be more likely to put it on your cereal or your hamburger.

Illustration: https://en.wikipedia.org/wiki/Berry_(botany) Berry True A berry is a specific category of fruit. They are simple fruits, which form from a single ovary in a single flower. Because their pericarp is soft all the way through, they are further classified as fleshy simple fruits. Fleshy simple fruits are the true berries of the botanical world, and they include, among other things: grapes, tomatoes, persimmons, peppers, and eggplant. To help organize the riotous fruit salad of botanical science, there are further subsets of berries. Pepos and hesperidium are modified berries, meaning that they have all the characteristics of berries, but also share additional characteristics amongst themselves. Pepo describes the berry structures of fruits such as squash, cucumber, watermelon, and pumpkins; these fruits have edible pericarps and rinds formed from the outer layer of their skin which may or may not be edible. Hesperidium refers to berries with a leathery skin and sectioned flesh surrounded by pith – think citrus fruits, like grapefruit, oranges, lemons, and kumquats. When is a Berry not a Berry? If it looks like a berry and tastes like a berry, it may nevertheless not be a berry – at least, not botanically speaking. It could, instead, be one of a number of other types of fruits – including drupes, pomes, aggregate fruits, accessory fruits, andepigynous or false berries. A drupe is a fruit with a juicy pericarp and a hard endocarp (which is the inner layer surrounding the seeds). Drupes include stone fruits such as cherries, peaches, olives, and mangoes. Coconuts are also considered drupes, since they consist of a hard endocarp surrounding the seed embryo, which is embedded in the coconut flesh. The outer layers (the mesocarp and exocarp) are generally removed prior to sale. A pome is a fruit that has its ovary at center, embedded in a core. Apples and pears are common pomes. You can, technically, eat the inner core that contains the seeds, but most people prefer not to. An aggregate fruit emerges from the fusion of multiple ovaries in a single flower; unlike true berries, they do not conform to a one-ovary-one-flower rule. Blackberries and raspberries, for example, are formed from tiny individual drupes called drupelets, which each consist of a juicy pericarp surrounding a hard seed. Related to aggregate fruits are accessory fruits. Accessory fruits, such as strawberries and pineapples, are created when tissue surrounding the plant ovary is incorporated into the formation of the fruit. You may hear of an accessory fruit referred to as a pseudocarp – a botanical term which means false fruit – which isn't accurate since accessory fruits definitely are fruits. They just aren't berries. 

An epigynous or false berry is formed from a flower with an inferior ovary. This doesn't mean that the ovary is bad or unhealthy; rather, it describes its position below the rest of the flower (in contrast, superior ovaries sit above the surrounding flower tissues and semi-inferior ovaries sit at the same level as them). Epigynous berries incorporate some of the surrounding flower tissue into the bodies of their fruits. The little star patterns on blueberries, cranberries, and the ends of bananas give them away as epigynous fruit; the mark is actually a part of the flower that the fruit has held on to. Seek out Botanical Berries Now that you know what to look for in a true berry – and a number of not-so-true berries – you'll be able to identify them anywhere. Take a look around the next time you go grocery shopping. How are all of the berries classified in the produce section? Grocery store definitions don't always line up with botanical truths. Think about why that might be. Once you're home, take a look at some of the fruits and vegetables you bought. Are any of them true berries, or other types of fruits labelled as berries? Cut open a pepo and a pome if you have them to see how their inside structures differ. And make sure to enjoy your tasty purchases, whether you put them in a pie or on the grill! Grilled Eggplant 3 pounds eggplant, cut into 1/2-inch slices 3 tablespoons coarse salt, plus more for serving 1/3 cup extra-virgin olive oil Ground pepper Sprinkle eggplant slices with salt on both sides. Place in a colander set over a bowl; let stand 1 hour to drain. Discard liquid andrinse eggplant slices under cold running water. Place on several layers of paper towels, and press out the water. Preheat a grill or grill pan over medium-high heat. Generously brush both sides of eggplant slices with oil and sprinkle with pepper. Place on grill and cook until browned (5 to 6 minutes). Flip eggplant slices and cook until browned on bottom. Serve hot, drizzled with olive oil and sprinkled with salt and pepper. Recipe courtesy of Martha Stewart Living. Berry Salad (Although you should probably call this “Accessory and Aggregate Fruit Salad”) 1/4 cup fresh mint, chopped 2 tablespoons sugar 1/2 (16-ounce) container strawberries, hulled and chopped 1 (6-ounce) container blackberries 1 (6-ounce) container blueberries 1 (6-ounce) container raspberries Crush mint and sugar in a mortar and pestle until well-blended (or place sugar and mint in a blender or food processor and pulse until well-blended). Place mint-sugar in a large bowl and add strawberries, blackberries, blueberries and raspberries. Gently toss until evenly combined. Recipe courtesy of Whole Foods. Sources: 1. http://study.com/academy/lesson/fruit-definition-types-benefits-examples.html 2. https://www.hort.purdue.edu/newcrop/morton/banana.html 3. http://waynesword.palomar.edu/fruitid1.htm 4. http://www.loc.gov/rr/scitech/mysteries/coconut.html 5. http://www.botanical-online.com/flores1angles.htm 6. McGee, Harold (November 16, 2004). On Food and Cooking: The Science and Lore of the Kitchen. Simon and Schuster. pp. 247–248. ISBN 0-684-80001-2. 7. S.J. Meades, D. Schnare, and K. Lawrence and C. Faulkner. (2004 onwards). Northern Ontario Plant Database Website. Version 1, January 2004. Algoma University College and Great Lakes Forestry Centre, Sault Ste. Marie, Ontario, Canada.

By Jenna L, Writer Edited by Carolyn Dallimore

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How Snow Works

The formation of snowflakes seems relatively simple. Water vapor in clouds freezes, and then crystallizes into ice.

But snowflakes are made up of such unique shapes, the formation of which are heavily dependent on a host of environmental factors. These include:

ambient conditions (temperature, humidity) in the cloud itself, which must be optimal for snowflake formation.

the presence of dust particles, which are needed to catalyze the development of snowflakes.  

Snowflakes come in a variety of different patterns, including the famous hexagonal plate structure, a rod-like structure, or a combination of the two. Depending on temperature and humidity, snowflakes develop differently.

An experiment conducted by Uchikiro Nakaya in the 1930’s determined the relationship between snowflake shape and specific meteorological conditions. By growing and isolating snow crystals in the lab under various conditions, Dr. Nakaya was able to determine that changes in temperature of only a couple of degrees could influence the shape of a snowflake.

Dr. Nayaka found that temperatures of around -2 degrees Celsius tended to yield simpler shapes, such as plate-like structures. By contrast, a temperature of -5 degrees Celsius allowed for the emergence of a six-needled hexagon. More intricate shapes tend to emerge as the temperature decreased further.

Humidity also plays a huge role in snowflake formation. The higher the humidity, the more intricate the design of the snowflake. Nakaya was able to establish a snowflake typology derived from his experimental work that is based on snowflake morphology (i.e. shape). Uchikiro Nakaya’s work on ice crystals and snowflakes revolutionized our understanding of these meteorological phenomenon.

You can grow your own crystals at home and examine their structure using only a cup of hot water and some Epsom salt. Combine these two ingredients and let the mixture sit for about three hours. Try varying the temperature by storing some batches in the refrigerator and others at room temperature. Compare the crystals that form among the different samples and note the similarities and differences. Using these techniques, see if you can replicate Nakaya’s results.

References: 

Libbrecht, K.   The formation of snow crystals. American Scientist, January-February (2007).

Mathematical Model Computes Snow Flake Shapes for the First Time. Physics4Me blog, February 16 (2012).

Furukawa, Y. and Wettlaufer, J.S.    Snow and Ice Cyrstals. Physics Today, December, 70-71 (2007).

Science Project: Make Your Own Crystals. Kid’s World blog.

Image of various snowflake patterns courtesy Earthzine and the University of Manitoba.

By Akshata Y, Staff Writer.

Edited by Bradly A.

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Death Valley’s Sailing Stones

image source

Racetrack Playa, a seemingly barren three mile long stretch in California’s Death Valley, and its famously mysterious sailing stones have long captured the interest of both scientists and geology enthusiasts, who have attempted to explain the phenomenon since the 1940’s. Theories explaining the long tracks following each rock ranged from alien interference to magnetic forces.  However, because no one had actually seen the stones moving, it was almost impossible to determine the true cause of the moving stones.

For many years, the prevailing theory was that the rocks somehow slid across ice, but this was never actually proven to be true. In 2006, planetary scientist Ralph Lorenz attempted to explain the sailing stones using the weather stations he set up in Death Valley. Lorenz studied the movement of the rocks, while comparing the phenomenon to other environments in which stones moves in a similar way, specifically the arctic tidal areas. He then created a simple model for his findings, based on an easy kitchen experiment that you can recreate using the instructions below. In 2013, a team of scientists verified Lorenz's work by using GPS technology to track the movements of stones placed on the dry lakebed. Using time lapse photography, the team was able to capture one of the first videos of the moving stones, which you can watch here. It was determined that ice and wind helped propel the rocks across the Racetrack Playa. Small jagged pieces of ice provide a slippery surface for the stones to hydroplane across as the wind pushes them. DIY Sailing Stones You can recreate the easy experiment Ralph Lorenz used to test his theory at home.

Find a small rock and place it into a small tupperware container.

Fill the container with water until only a little bit of the rock is sticking out.

Freeze the container until the ice is solid and take the ice out of the container.

Take a bigger bowl and coat the bottom with sand, then fill the rest with water.

Place the rock and ice into the bowl upside down and gently blow.

The rock should move and create small tracks in the sand.

References http://www.livescience.com/45876-sailing-stones.html http://www.nytimes.com/2014/09/02/science/death-valley-mystery-why-rocks-move.html?_r=0

By Akshata Y., Staff Writer Edited By Peggy K, Editor

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How the Ichthyosaur Got Its Fins

Have you ever wondered how aquatic reptiles evolved? No? Why not? Regardless, a new fossil discovered in 2011 is shedding light on these questions [1].

Ichthyosaurs are a class of extinct reptiles that ruled the oceans 250 million years ago [2]. Some were as large as blue whales. However, their evolution from the reptilian common ancestor has posed a problem: reptiles evolved on land while ichthyosaurs were ocean dwellers. The intermediary evolutionary steps have been a mystery. 

The mystery remained until 2011, when a fossil found in China showed what is believed to be a proto-ichthyosaur. This transitional specimen, with flippers for forelimbs and small hindlimbs, suggests that the link between ichthyosaurs and reptiles was a sea dwelling animal in the process of evolving into what would become the terrifying apex predators of the sea.

The Cartorhynchus lenticarpus [3] fossil (loosely translated as “short snout, flexible wrist”), shows that ancestral ichtyosaurs were aquatic, although they still shared traits in common with early terrestrial reptiles.

Paleontologists believe that this shows that ichthyosaurs evolved from reptiles that were already primarily aquatic, and that the old theory of walking semi-aquatic sea dinosaurs must therefore be incorrect.

The more we learn about the specifics of the history of life on earth, the more complete the picture we can put together of the origins of the spectrum of modern biodiversity will be.

NOTES:

[1] Perkins, S. How the ichthyosaur got its fins. Science News, November 5 (2014).

[2] Ichthyosaur Wikipedia page.

[3] Dell’Amore, C.   First Amphibious “Sea Monster” Found; Fills Evolutionary Gap. National Geographic, November 5 (2014).

Submitted by Kelsey M, Discoverer

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Guided by the Sun: Celestial Navigation

Ever wondered how mariners so expertly navigated the seas? Or how the people of ancient civilisations made their way across vast deserts? The answer is right above you!

Imagine that you have travelled back to the year 1766. You find yourself aboard the ship of Captain James Cook, who has been asked by the Royal Society, the world’s leading scientific institution of the time, to voyage to the Pacific Ocean to observe one of the rarest of events, a transit of Venus. But you have only just left England and are now off the shore of Spain. You see a man standing near the railings, holding a strange instrument. He is the ships navigator, and he is engaged in a practice called celestial navigation. You immediately want to know more!

Celestial navigation is the use of the sun and stars as guides to navigate by both land and sea. By knowing the position of the sun, and perhaps a few stars, it is possible to navigate the Earth to an astonishing degree of accuracy. The navigator is holding a sextant, which allows him to measure the angle between two points. In this particular case, the navigator is concerned with the angle between the horizon and the sun. Without this measurement, it would be impossible to determine where the ship is, and the voyage would end in disaster!

We can measure the position of any point on the Earth by taking note of two things: the position between the poles, called latitude, and the position around the Earth, called longitude. While latitude is measured in degrees, longitude is measured in hours. This is because there is a natural bound for latitude: namely, the poles. But for longitude, you could keep going around the Earth without end! Because the Earth makes a full rotation in 24 hours, it is natural to divide up the Earth’s surface by hours. With these two measurements, we can travel the world!

In order to find latitude, we must first think about how the Earth goes around the sun. The Earth orbits the sun once every 365 days and turns about itself every 24 hours. To make this easier, let us pretend that the sun is always above the equator, which is the imaginary line drawn across the middle of the Earth. If we were to look up at our daytime sky, we could work out that the sun is at a right angle to the North Celestial Pole (NCP). Then we can work out that the angle between NCP and the horizon is actually our latitude. This may not make much sense immediately (I have to always draw it out!), so let’s take a look at a diagram:

  But this isn’t quite the whole truth. The Earth is tilted away or towards the sun depending on the time of year, which not only means that we experience the changes of the seasons, but also that the sun’s height in the sky changes over a year. But not to worry, that just means that we need a slight correction to our measurement, noted by declination or Dec. We can make this correction by referring to a book called the Nautical Almanac. It is a collection of data for each day which allows mariners (or curious individuals!) to make this conversion.

So to put it all together: we measure the height of the sun by using a sextant, and then by referring to our Nautical Almanac, we correct the angle we measure, and then we can calculate our latitude. But we only know one of the two things we need to pin down our location. We don’t yet know if we’re off the coast of Spain or Japan!

To complete our task, we should find where around the Earth we are. Now if you’re still aboard our ship (and haven’t time-traveled to some more exotic place in time), you would find that the navigator is trying out a newly devised method of finding longitude. He’s skeptical, but we are here to help. The navigator begins by measuring the height of the sun until he is certain that the sun is at the very top of its daily path across the sky. This indicates that it is local noon, which is similar to our usual concept of noon, except that it is exactly noon at our present location.

This can be explained by our use of time-zones. The sun doesn’t move into one time zone at noon, then one hour later magically teleport above the next time zone at their noon. No, the sun passes smoothly through the time-zones. If I’m on one edge of a time zone and you are on the other, while our watches may read 12 pm, we will not agree on local noon. This means that it is only true noon at one line of longitude at a time.

Our navigator, knowing that it is now local noon, rushes to his cabin and opens up a very peculiar box. Inside is a state of the art piece of equipment, called achronometer. It is a very finely tuned clock that is always set on the time at Greenwich in England, where the Royal Observatory is located. By knowing the time in Greenwich when it is local noon on the ship, the navigator is able to calculate the difference and work out the exact position of the ship around the Earth. He can do this because if we divide up the Earth into 24 equal parts, as mentioned before, we can see that if we know noon at one point and a different time at a known location, we can work out how far away we are from that location.

And so every day, the navigator informed the captain as to the position of the ship. Eventually, this allowed Captain Cook to sail south around South America to the Pacific. There, he and his crew made camp on the island of Tahiti, where he not only observed the transit of Venus, but also learned about the culture of the natives. Although we might not think of the 18th century Tahitians as advanced, they had names for many of the bright stars in the night sky. During their stay, the crew and the Tahitians bonded, working together to secure the observations that Cook was sent there to obtain. Science is not only a means of discovery, but it is also a means of connecting with the natural curiosity that exists inside all of us.

Happy discovering!

  REMINDER: DO NOT LOOK DIRECTLY AT THE SUN!

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Make Your Own Astrolabe

So if you, like our navigator, want to be able to measure the angle between two points, such as a star and the horizon, then follow these steps to make your own navigational instrument!

If you’re under 10, please get a parent to help!

Materials

1 plastic straw

1 roll of dark string

1 pair of scissors

1 piece of cardboard

1 bottle of glue and/or tape

1 hole punch/pen

1 washer or nut

1 astrolabe printout (http://cse.ssl.berkeley.edu/AtHomeAstronomy/act07_astrolabe.html)

Directions

Print and cut out the astrolabe design.

Mark and cut out astrolabe shape on cardboard.

Using a hole punch (or other sharp object), pierce the hole on the cut-out and the cardboard.

Line up the two cut-outs and glue them together.

Thread the string through the holes and tie at the end.

Cut the thread a few inches from below the cut-out.

Tie the washer to the string.

Glue the straw along the edge of the cut-out where indicated.

Let dry!

How to Use Your Astrolabe

Let the washer hang freely.

Look through the straw at some star or building (NOT THE SUN).

With your finger, hold the string to the edge of the cut-out.

Read the angle that you just measured!

Some Ideas

Try measuring the angle of the tallest building you can see.

Go outside and measure the angle of your house. How does that angle change when you get closer? Further away?

At night, try measuring the angle of a star.

Come up with your own ideas, and tell SciNote all about it!

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IMAGE CREDITS:

Eight Bells, by Winslow Homer 1886

Latitude and Longitude, by Layers of Learning (http://www.layers-of-learning.com/latitude-and-longitude/)

Finding Latitude, John Weaver 2014

Chronometer, John Weaver 2014

Astrolabe: http://howtosmile.org/record/7251

 By John W, Staff Writer.

Edited by Peggy K.