Thermogenesis Phenomenon

Between late February and May, in woodlands and wetlands throughout eastern Canada and the northeast United States, you’ll find a low growing, foul-smelling plant called skunk cabbage (Symplocarpus foetidus). The skunk cabbage is one of the first plants to emerge in the spring when the winter snow is yet to melt. As the plant pokes its head out of the snow and starts flowering, it forms a small pool of water around it, created by snow melt. The heat needed to melt the snow is derived not from the sun but generated by the plant itself. Skunk cabbage is one of the few species in the Plant Kingdom, belonging to ancient lineages of flowering plants, that has the rare ability to generate heat — a phenomenon known as thermogenesis.

The flower of a skunk cabbage melts snow around it by its heat.

Thermogenic plants are found in a variety of families, but Araceae in particular contains many such species. Skunk cabbage, the dead-horse arum, the elephant yam and Philodendron selloum, are a few examples of thermogenic plants belonging to the Araceae family. These plants can generate significant amounts of heat that even mammals can’t, and their rate of heat production actually increases the colder the environment gets.

In an experiment, skunk cabbages were found to maintain flower temperature 9°C higher when the air temperature was at 15°C. When the air temperature was dropped to –15°C, the flower was still at 15°C, or 30° higher than the air temperature.

The Asian sacred lotus (Nelumbo nucifera) can also regulate its flower temperature. Measurements showed that flower temperatures stayed at a warm 30°C to 36°C even when environmental temperatures dropped as low as 10°C. Another species Philodendron selloum is even better at temperature regulation. In lab tests, the flowers managed to stay between 30°C and 36°C even when scientists chilled the air to 4°C.

The dead horse arum (Helicodiceros muscivorus), another obnoxious smelling plant, reportedly produces more heat than any other known plant or animal considered in its entirety.

Knowledge of heat generating plants date back more than 200 years but it’s only recently researchers have started to unravel the biochemistry behind it. It’s now know that the heat is generated in the mitochondria, as a secondary process of cellular respiration, although the actual process is still poorly understood.

Biologists believe thermogenic plants generate heat to assist in pollination. The heat renders the flower’s fragrance more volatile which helps the scent to spread more widely so that pollinating insects can find them from far away. The dead horse arum, which smells like rotten meat, uses heat not only to attract flies and beetles but also to convince them that it’s a dead carcass. The heat also makes the thermogenic plants attractive to insects seeking warmth and comfort.

But a flower that offers pollinators just a sip of nectar or a snack of pollen and then sends them on their way has a better chance of dispersing its pollens than a flower that traps insects for a whole night by its hospitality. This is why thermogenesis is not commonly seen among plants. During evolution these heat generating species died out and were replaced by plants having better pollination methods.

The dead-horse arum. This flower has the fragrance of a rotting carcass.

Skunk cabbages blooming in the forest.

Skunk cabbage breaking through the ice.


The Tree of Life in Kalaloch

There is an extraordinary tree in Kalaloch beach, within Olympic National Park in Washington, that some people call “the tree of life” because of the miraculous way it seems to be hanging on to life when it should have been dead years ago. The tree is located just north of Kalaloch Lodge, near the Kalaloch Campground, on a cliff that has partially caved in due to erosion — right under the tree. The tree is anchored to the ground by only a few tendrils of roots, but the majority of them are exposed and spread out over a void. It’s a miracle that the tree is still breathing and thriving and sprouting fresh green leaves every spring despite having no soil underneath. No one knows why the tree has not toppled over during the intense storms that the coast is known for.

The tree is a Sitka spruce, but there is no official name. So people have been calling it by various names such as “the tree of life” and “the runaway tree”. Underneath the tree, is a cave like hollow that some people call “the tree root cave”. I couldn’t find how old the tree is or for how long it is hanging there for dear life.

The cave under the tree was caused by a small stream that empties into the ocean and has been washing the soil out from underneath it. I gather that this happened many decades ago, as can be inferred from this passage I read at, written in 2005:

As we approached the tree, a couple that was walking towards the bluff commented that they had been coming to this campground for 17 years and each year they had been expecting the tree to fall, but it hadn’t happened yet.


Unexploded Bombs Find Everyday Use in Laos

The Vietnam War ended 40 years ago, but left a deadly legacy, especially in Laos. The US military dropped more than 2 million tons of bombs on the country during the war between 1964 and 1973, making Laos the most heavily bombed country in the world on a per capita basis. There were more than 580,000 bombing missions on Laos, equivalent to one bombing mission every eight minutes, 24 hours a day, for nine years. Not all of those bombs did what they were supposed to do. An estimated 30 percent of ordnance failed to explode, remaining live in the ground years after the war. They continue to detonate at unexpected places and at unexpected times, such as when children are playing.

Boats made from bomb casings seen in a village in Laos.

A major cause of casualties, however, is villagers attempting to open the big bombs to sell the metal and the explosives inside to scrap dealers. A high quality bomb casing weighing up to 2,000 pounds can fetch more than $100. Empty bomb casings that once contained deadly explosives are visible all across the country in new forms — from hollowed out canoes and containers, to props holding houses above flood.

When photographer Mark Watson took a bicycle trip across the country, he was surprised to see these lethal devices being reused in extraordinary ways. “Scrap from such widespread bombing has been utilized in people’s homes and villages,” Watson said, “for everything from house foundations to planter boxes to buckets, cups and cowbells.”

Gathering bomb scraps is a deadly occupation, but the people were forced into the trade by poverty.

"Lots of agricultural land is denied to people because of the presence of UXO (unexploded ordnance), and this is the main problem. It prolongs poverty because people can't do what they need to do. If they know that UXO is present, they will not plow deeply enough to get a good quality crop," said David Hayter, of Mines Advisory Group (MAG), an NGO working to detect and remove mines and bombs.

But progress is slow and their budget limited. Meanwhile, people continue to get killed and injured by accidental detonation of live ordnance. As of 2012, at least 29,000 people have died from such accidents.

Children pose near unexploded bombs recovered from around the village.

A house in village uses a bomb casing as a garden decoration. 

Bomb casing used as a flower pot. 

Bomb casings used to prop up a house.

Bomb casings as water container. 

Metal recovered from bomb casing shaped into cow bells.

Bomb casings used to prop up houses.

A bomb casing turned into a boat.