Alarming Avocados

Not all avocados are green and pear-shaped. Some are spherical, black and even purple. Photo by ruurmo. Aguacates para todos. CC. https://flic.kr/p/fN5wX (pile)

Not all avocados are green and pear-shaped. Some are spherical, black and even purple. Photo by ruurmo. Aguacates para todos. CC. https://flic.kr/p/fN5wX (pile)

 

Scooping the flesh out of an over-ripe avocado the other day, I thought, what a weird fruit. The more I researched the avocado, the more I realized that yep, this plant really is weird. Here’s why.

Origin Story

Crazy fact: the avocado was domesticated so long ago that we don’t know what its wild ancestor looked like.

Humans in Mexico were growing avocados long before history was being recorded. They called it ahuacatl, and it’s still called that in some parts of Mexico.

The Incas discovered avocados between 1450 and 1475 when they happened to take over an area where the fruit were grown. The Inca called the fruit aguacate. The fruit was grown from the Rio Grande to central Peru before Europeans arrived.

The European explorers were quick to adopt the aguacate. They liked by the buttery texture but the native name eluded them. Various mangled versions of the name ‘aguacate’ started popping up in European documents.

The avocado quickly spread from Mexico to other areas with the same climate. A bunch were planted in the West Indies. In 1833 they were introduced to Florida, and California got some in 1871. Today avocados are grown around the world, from New Zealand to Indonesia. Mexico is the leading exporter of avocados, followed by California, Israel and South Africa.

How about an alligator pear sandwich?

What do you call a bumpy green fruit? Photo by torbakhopper HE DEAD. CC. https://flic.kr/p/fpwPr

What do you call a bumpy green fruit? Photo by torbakhopper HE DEAD. CC. https://flic.kr/p/fpwPr

Remember how the European explorers had trouble with ‘aguacate?’ Well, the name mangling got worse, as common names often do.

By the beginning of the 20th century, there were at least 40 different names for avocado. These included avigato, albecatta, avocatier, avocatt, midshipman’s butter, vegetable butter, butter pear and my personal favorite, alligator pear. Well, it’s pear shaped and scaly like an alligator, right? Makes sense.

The showdown to choose the correct name happened in the United States. California called the fruit aguacate, while Florida liked alligator pear. Neither of them wanted to change the name. However the powers that be in the U.S. Department of Agriculture decided that alligator pear was unpleasant, and suggested avocado instead. After some scuffles, the name avocado became the industry standard. In a different world, we would have alligator pears in our sandwiches.

A flower with an identity crisis

Avocado flowers. Photo by Cayobo. Avocado Flowers. CC. https://flic.kr/p/zbPB

Avocado flowers. Photo by Cayobo. Avocado Flowers. CC. https://flic.kr/p/zbPB

Avocados make over a million flowers, but less than 0.1% ever become fruit.

Like a lot of flowers, each avocado flower has both male and female organs. Here’s where it gets crazy: the parts don’t work at the same time. The flower only opens for two days. On the first day, only the female organs work. For two to three hours. On the second day, only the male organs work. No other plant does this. I told you avocados were weird. The botany word for this is dichogamous. Isn’t science grand?

Because of this unique pollination system, if a tree is all on it’s lonesome, it’s out of luck. It can’t pollinate itself, so it won’t have any fruit. Growers have to be careful to mix varieties whose male and female organs work at the same time of day. Thankfully there are over 1,000 different avocado varieties, so this isn’t too hard to do.

Berry nice to meet you

The creamy avocado is a fruit, but what kind? Photo by Jaanus Silla. Avocado. CC. https://flic.kr/p/68eBn2

The creamy avocado is a fruit, but what kind? Photo by Jaanus Silla. Avocado. CC. https://flic.kr/p/68eBn2

Avocados are actually berries. In the world of botany, berries are fleshy fruit that grow from a single ovary. Think blueberries, tomatoes, bananas, and even pumpkins.

You can try planting an avocado seed, but it will be five to 13 years before you’ll get a fruit out of it. If you’re impatient like me, you can always pick up one up at a grocery store. It will take 7-10 days to ripen at room temperature. To make it ripen faster, put it in a bag with another ripe fruit like an apple or banana.

Tree time

Avocado tree in bloom. Photo by Cayobo. Avocado Tree In Bloom. CC. https://flic.kr/p/mg7qZw

Avocado tree in bloom. Photo by Cayobo. Avocado Tree In Bloom. CC. https://flic.kr/p/mg7qZw

Avocados grow on trees. They can be up to 60 feet (20 metres) tall, but farmers usually prune their trees to keep them under 15 feet. These trees are tanks. 400-year old wild avocado trees in Mexico are still making fruit.
When a tree is 5-7 years old it yields 200-300 fruit per year. However, the trees like to take a break, so a bumper-crop year is usually followed by a slow year. This can be a problem because avocado demand doesn’t have yearly cycles. People want their guacamole, and they want it now.

Economic boom and bust

The alternating cycle of avocado trees makes life hard for avocado farmers. The industry loses millions of dollars during low crop years. Researchers are trying to find ways of getting the trees to produce the same every year, but no luck so far.

In 1965 California found an innovative solution to the problem of too many avocados in bumper-crop years; freezing then in liquid nitrogen. They could be thawed later to use in restaurants and airlines. Wait, they serve avocados on airplanes? I must be taking the wrong flights.

Sugar or spice. Or both.

People use avocados for all sorts of things, even ice cream. Photo by Kimberly Vardeman. Avocado Ice. CC. https://flic.kr/p/9VsoZE

People use avocados for all sorts of things, even ice cream. Photo by Kimberly Vardeman. Avocado Ice. CC. https://flic.kr/p/9VsoZE

The cool thing about avocados is there is no right way to eat them.

In North America we eat them in salads and sandwiches. In some places in South and Central America an avocado with salt, tortilla and a cup of coffee is a complete meal.

In Brazil, it’s a dessert mixed with ice cream and milkshakes. They have avocado ice cream in New Zealand too. In Java, avocado is mixed with sugar and black coffee.

Ever wonder why we eat avocados raw? Ever thought of cooking one? Well, I wouldn’t try it. Avocados get bitter when they’re cooked, because they’re full of chemicals called tannins.

Weird by-products

Think there's no avocado in this soap? Think again. Avocado oil is popular in lots of products. Photo by Erin Costa. Pink Strawberry Soap_KRISTIE 2. CC. https://flic.kr/p/bmC7W4

Think there’s no avocado in this soap? Think again. Avocado oil is popular in lots of products. Photo by Erin Costa. Pink Strawberry Soap_KRISTIE 2. CC. https://flic.kr/p/bmC7W4

Avocado oil keeps for a long time, up to 12 years at four degrees C. Because of this stability, avocado oil is used to make facial creams, hand lotions and fancy soap. In fact, 30% of the Brazilian crop is made into oil. The leftover flesh is used to feed farm animals once the oil has been squeezed out.
Strangely enough, the avocado’s huge seed contains a white fluid that turns dark red when exposed to the air. The Spanish conquistadors used it as ink.

Now you have something to ponder over your next bowl of guacamole, or avocado milkshake.

References
http://ucavo.ucr.edu/General/ThreeGroups.html
http://ucavo.ucr.edu/General/FruitBerry.html
http://ucavo.ucr.edu/General/Answers.html#anchor738397
http://ucavo.ucr.edu/General/HistoryName.html
http://ucavo.ucr.edu/General/Introduction.html
https://www.hort.purdue.edu/newcrop/morton/avocado_ars.html
http://ucavo.ucr.edu/AvocadoVarieties/Hass_History.html
http://www.britannica.com/EBchecked/topic/45866/avocado
https://www.hort.purdue.edu/newcrop/morton/avocado_ars.html
https://www.hort.purdue.edu/newcrop/morton/avocado_ars.html
http://ucavo.ucr.edu/Flowering/Figure3.html
http://ucavo.ucr.edu/Flowering/FloweringBasics.html

8 things you didn’t know about acorns

Acorns are very common in southern Canada, but how much do you know about them? Photo by moonimage, acorns, CC, https://www.flickr.com/photos/moonimage/9166449223/

Acorns are very common in Southern Canada, but how much do you know about them? Photo by moonimage, acorns, CC, https://www.flickr.com/photos/moonimage/9166449223/

 

“Are acorns nuts?” my roommate asked out of the blue.

The science nerd in me struggled to remember the botanical definition of a nut.

Being a normal human being, my roommate was interested in more practical matters; “If kids are bringing them into a nut-free daycare, will kids with nut allergies react to them?”

Good question. I had no idea. But Google did.

The short answer is no, allergies to acorns are quite rare. There has never been a recorded death related to an acorn allergy. Therefore, kids with tree-nut allergies who pick up and play with acorns will be fine.

However, acorns are still a tree nut, so just in case kids shouldn’t be eating them! Thankfully acorns are very bitter, and not likely to be ingested. We’ll get to that later.

Being an inquisitive botany geek, I naturally wanted to learn more about acorns. Let’s learn together, shall we?

1. Acorns are nuts, but almonds aren’t!

The hard case of this acorn is split open, revealing the yummy fruit inside! Photo by John, cygnus921, Acorn 020, CC, https://www.flickr.com/photos/cygnus921/2955260269/

The hard case of this acorn is split open, revealing the yummy fruit inside! Photo by John, cygnus921, Acorn 020, CC, https://www.flickr.com/photos/cygnus921/2955260269/

It turns out that botanically a nut is a very special beast. A nut is a hard, dry pod that surrounds the fruit and a single seed inside. Think chestnuts, hazelnuts and acorns! Almonds are actually drupes, like plums and peaches.

2. Meet the family

There are 450 species of oak trees wordwide, but only 13 in Canada. Most of our native species hang out in the most southern parts of the country. The Cork Oak (Quercus suber) is where all your wine corks come from, and the waterproof wood of the White Oak is used for wine barrels.

3. Geeky Canadian trivia

Quick, which province does this flag represent? Photo by Nicolas Raymond, Prince Edward Island Grunge Flag, CC, https://www.flickr.com/photos/80497449@N04/7384695152/

Quick, which province does this flag represent? Photo by Nicolas Raymond, Prince Edward Island Grunge Flag, CC, https://www.flickr.com/photos/80497449@N04/7384695152/

Quick, which Canadian province has acorns on its flag? If you guessed Prince Edward Island, you’re right! There are four oak trees on the flag, one represents England and three others represent the three counties of Prince Edward Island. The Red Oak, a native tree prized for its wood ideal for furniture making, is also the province’s official tree. Who knew?

4. Sexy acorns

Can you guess which part of the male anatomy was named after the acorn? It’s the glans, or head of the penis! Glans the Latin word for acorn. I guess the 17th century English thought there was some resemblance. No, I’m not going to draw you a picture.

5. Essential fall food!

Birds and beasts of all kinds love snacking on acorns. Photo by Ingrid Taylar, A Caching Steller’s, CC, https://www.flickr.com/photos/taylar/7331902826/

Birds and beasts of all kinds love snacking on acorns. Photo by Ingrid Taylar, A Caching Steller’s, CC, https://www.flickr.com/photos/taylar/7331902826/


We often see squirrels with acorns, but did you know that deer eat them too? 25% of a deer’s fall diet is acorns! Mice, woodpeckers, blue jays and ducks like to snack on them too. Oak trees depend on animals to carry their acorns somewhere else, bury them, and then forget about them so a new tree can start growing.

6. Essential human food!

Acorns have been eaten by many different cultures for thousands of years. In North America, some groups of Aboriginal peoples depended on acorns. For example, it is estimated that 75% of the Aboriginal people in California relied on acorns on a daily basis. Most oak trees only produce acorns every 2-3 years, so most groups found ways to store unshelled nuts for 10-12 years in granaries. Today the descendants of these groups use acorns as special traditional foods, but do not eat them every day.

7. Nutritional powerhouses

Acorns are packed with nutrients! Though not these ones, because they aren't ripe yet. Photo by woodleywonderworks, Fruit From Hurricane Irene (green acorns), CC, https://www.flickr.com/photos/wwworks/6094598165/

Acorns are packed with nutrients! Though not these ones, because they aren’t ripe yet. Photo by woodleywonderworks, Fruit From Hurricane Irene (green acorns), CC, https://www.flickr.com/photos/wwworks/6094598165/

There’s a reason so many people have eaten acorns throughout history- they are abundant and really good for you. Some acorns are 18% fat, 6% protein and 68% carbohydrate, equivalent to modern corn and wheat. They are also great sources of vitamin A and C.

8. Tricky tannins

There is only one problem about eating acorns-they mess with your insides! Well, not dangerously so, but they contain tannin, a bitter chemical that we humans use to tan leather. Too much tannin in your sensitive intestines makes it hard for them to get any nutrients out of the food you’re eating! So acorns may be super good for you, but if you’re eating them raw your body will never see any of those wonderful nutrients. You’ll also be left with a bitter taste in your mouth. Tannins are also found in berries and pomegranates, but acorns take tannins to the next level.

Well, that’s not very nice of oak trees, is it? It’s actually a clever defense mechanism. If all their acorns get eaten, none will turn into baby trees. So the bitter tannins are a way to discourage animals from eating their seeds. Pretty neat, huh?

Unfortunately for the oak trees, many animals have found ways to get around tannins. Some animals have special digestive systems that destroy the tannins before they can do their thing. Other animals like squirrels, deer and pigs eat so many acorns at once that it doesn’t matter that they aren’t absorbing all possible nutrients. Humans have a different adaptation-soaking the nuts in water to rinse out the tannins.

As we head into fall, hopefully you’ll look at all those fallen acorns in a different light!

References

http://www.csus.edu/anth/museum/pdfs/Past%20and%20Present%20Acorn%20Use%20in%20Native%20California.pdf
http://www.hastingsreserve.org/OakStory/Acorns2.html
http://books.google.ca/books?id=tnwAlLgWEhAC&pg=PA114&lpg=PA114&dq=penis+glans+named+after+acorn&source=bl&ots=kMGAkN3DzA&sig=Od-y1vkXd2y2KIQl-3wuCsVajSg&hl=en&sa=X&ei=5t4AVMilCs6_sQSm_4HoCA&ved=0CCMQ6AEwAQ#v=onepage&q=penis%20glans%20named%20after%20acorn&f=false
http://ontariosown.ca/uncategorized/nuts-about-acorns/
http://www.gov.pe.ca/infopei/index.php3?number=1599
http://www.gardenguides.com/101927-oak-trees-canada.html
http://www.ontario.ca/environment-and-energy/white-oak
http://ontariosown.ca/uncategorized/nuts-about-acorns/
http://www.britannica.com/EBchecked/topic/422776/nut
http://www.seriouseats.com/2010/04/what-are-the-differences-between-nuts-and-drupes.html
http://www.biology-online.org/dictionary/Nut
http://www.britannica.com/EBchecked/topic/423415/oak
http://www.schoolhealthservicesny.com/uploads/Acorns%20Pinecones.pdf
http://www.anaphylaxis.org.uk/what-is-anaphylaxis/knowledgebase/tree-nut-allergy–acorns?page=11
http://blog.onespotallergy.com/2012/11/newstalk1010-interview-are-acorns-a-risk-if-youre-allergic-to-tree-nuts/

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