Trees, you can't live without them. They are the opposite from people in respiration, breathing in our carbon dioxide and breathing out oxygen that humans need. I'm sure that's what they told me in science class.

Just in case trees can't do the job of extracting carbon emissions from the air, someone has invented the synthetic tree:

"As the wind blows though plastic "leaves," the carbon is trapped in a chamber, compressed and stored as liquid carbon dioxide." This particular tree does not look like a tree, but there are some that do. If whoever is in charge of these things would just employ these types of air cleaning devices, there would be no need to start taxing people for carbon footprints.

Trees are just plants that often grow very tall. That should be the end of story, but in the past, people have made them mythical and symbolic, and sometimes frightening things, especially when gathered together and call a forest.

These are some thoughts on trees I collected when writing a paper on J.M. Synge's play Riders to The Sea:

References to the northern cult of Odin appear in the play Riders to The Sea. Odin is linked to many other mythological figures and motifs, including the Green Man hidden in foliage and trees.

Yggdrasil was the name of the tree in the saga of Odin. Sacred trees and groves figured in the beliefs of the pagans. The Mythic Image explains Yggdrasil as the World Ash and describes the worm gnawing at its root as a dragon, "the Old Germanic world ash, Yggdrasil- where the dragon Nithogg gnaws at the root..." (Campbell).

The Mythic Image by Joseph Campbell gives examples of tree worship and inversion. This inversion turned things topsy-turvy. Trees were said to grow downward and have roots above and branches downward.

This calls to mind the Tarot cards which can be read inverted and have a different meaning than those read right side up.

The Green Man motif, found in many cultures, shows a man enmeshed in foliage or vegetation. This theme is primal or archetypal to civilization's worship of all phases of the birth, reproduction, and death cycle. The forbidden fruit hanging upon the tree in Eden, Christ crucified hanging upon the tree in Golgotha, and Odin hanging on the tree of Yggdrasil all belong to the Green Man theme, man and tree united in concept.

Albrecht Durer's Crucifixion painting shows a Christ upon the cross amidst a group with foliage in the background. His Agony In The Garden depicts several symbols that are both pagan and Christian. Among them are a tree, chalice, cross, and sword.

Trees played a part in pagan theologies. The body of Osiris was said to be encased in a tree trunk in Dictionary of Mythology, Folklore and Symbols:

"TAT (Dad, Daddu, Tet, and Zad)...Osiris's backbone, the tree trunk in which his body supposedly had been enclosed..." (Gertrude Jobes, the Scarecrow Press, Inc., New York, 1961, p 1537).

The Green Man, Robin Hood and Sherwood Forest, the Haunted Woods, all of these have themes with trees as important symbols.

In ancient days, the forest was a dangerous place, especially at night. They contained many secrets. The leaders of various mythic cults would engender fear and awe of the forest for their own purposes.

Joan Baez, in her album Baptism, sings a warning to stay on the path and not venture into the woods, the same advice given to Little Red Riding Hood:

"The wood is full of shining eyes, The wood is full of creeping feet, The wood is full of tiny cries: You must not go to the wood at night!" (The Magic Wood, by Henry Treece)

Little Red Riding Hood was warned to stay on the path and not to go into the woods. In the Charles Perrault version of Red Riding Hood, the girl encounters an Old Father wolf. When the wolf arrives at grandmother's house and wants her to unlock the door, she says, ""Pull out the peg and the latch will fall." This is reminiscent of the Gordian knot puzzle.

Sherwood Forest, Yggdrasil, and images of spooky and magical forests are all part of tree legends of Northern Europeans. Trees were at times thought to contain spirits and gods. They were often held sacred. Groves of trees were the settings for the mystic rites of Druids and other cults, where strange and grisly proceedings were practiced.

During the Nazi regime of World War II, "trees" were constructed of poles set in the ground with concrete and having wooden pegs at the top for hanging victims in a kind of crucifixion.

A video excerpt from the film Paragraph 175 says:

"Heinz Dörmer, now a very frail 89-year-old, spent nearly 10 years in prisons and concentration camps. In a quivering, barely audible voice, he remembers the haunting, agonized cries from "the singing forest", a row of tall poles on which condemned men were hung: "Everyone who was sentenced to death would be lifted up on to the hook. The howling and screaming were inhuman. Beyond human comprehension."

This example shows that old pagan beliefs about woods and trees still had mythical power over the minds of people in the 20th century. The film, The Brotherhood of the Wolves, portrays people using the woods as an outdoor cathedral for their pagan rites.

A tree is just a tall plant that serves to remove carbon emissions from the air, but long ago, a tree was not just a tree.