We've all heard this expression without thinking much about what it means. It was originally used when a person wanted some good luck or when one hopes that something will go well. Our fondness for trees goes back to ancient ancestors, where trees may have provided a safe refuge, that people could climb to get away from danger. We use them for refuge today when we head for the shade of a tree if out in the midday sun.

Photo left: www.Gardenerspath.com (link below)

Obviously, trees have provided wood through all mankind's history, for building our shelters and creating fire. Even prehistoric trees play a part as they are converted to coal. However, now we are understating more and more about their contribution to the health of our planet and the very air we breathe to live.

Now we all know green plants, as well as algae and certain bacteria, take CO2 from the air, and release oxygen into the atmosphere. But how much does on tree release? Although there are different factors that can increase or decrease oxygen production, here are some amounts for a leafy mature tree:

-           One tree produces as much oxygen in a season as 10 people inhale in a year.

-           One tree can absorb CO2 at a rate of 48 pounds per year.

Most scholars believe “Knock on Wood” expression originated in pagan Germanic Cultures, but similar expression can be found all over the world in languages including Arabic Swedish, Trinidad and Tobago, and Brazil, demonstrating that people in many cultures share this awe and appreciation for trees. In the past, many people thought the protective properties came from tree spirits who inhabited the trees, and some of these spirits were reviled instead of revered.

• The Rowan tree was always believed to be a force for good which could protect people from enchantment. Pieces of Rowan wood were carried for personal protection.
• Maple: In parts of Europe it was the custom for maple branches to be hung around a doorway to prevent bats from entering the building.
• Holly: There is a widespread belief that cutting down a whole holly tree will bring bad luck! Hanging holly leaves around the house was also thought to keep evil spirits away and used as a charm against house goblins and witches.
• Ash: This tree was thought to have medicinal and mystical properties and the wood was burned to ward off evil spirits. In Norse Viking mythology, ash was referred to as the 'Tree of Life'. In Britain, it is known as a healing tree.

Lastly, in some contemporary fiction, we see the trees come to sentient life as Ents in Tolkien's Lord of the Rings Trilogy and as Whomping Willows in the Harry Potter books, and in Marvel comics and the Guardians of the Galaxy movies as Groot, an extraterrestrial, sentient tree-like creature.

Makes you want to go out and hug a tree. This last picture takes that expression to a new level.

 Photo: From flying Deer Nature Center, Chatam, NY: (Link below)

 Links:

Article and photo: The Secret Lives of Trees

https://flyingdeernaturecenter.org/the-medicine-pouch-of-the-wisdom-crow/

 

Article: Oxygen Produced by Photosynthesis

https://www.thoughtco.com/how-much-oxygen-does-one-tree-produce-606785

Gardeners Path web info and photo of tree trunk cut:

https://gardenerspath.com/plants/plant-folklore