The Truth About Coffee

Mmm mmm coffee. This wonderful elixir has taken over the world. Though individual tastes and preferences vary, there is no denying that most folks who turn to coffee enjoy its effects as a stimulant. Many an In Defense of Plants post has been written in a coffee-fueled frenzy. Even as I write this piece, I am taking breaks to sip on a warm mug of the stuff. Coffee has plenty of proponents as well as its fair share of nay sayers but the health effects don't really concern me much. Today I would rather talk with you about the shrubs that are behind all of this. 

The coffee we drink comes from a handful of shrubs in the genus Coffea. Native to parts of Africa, these shrubs are distant relatives of plants like buttonbush (Cephalanthus occidentalis) and the bedstraws (Galium sp.). The "beans" that we brew coffee from are not beans at all but rather a type of pit or stone found in the center of a bright red berry. Before they are roasted, the "beans" are actually green. Plants in this genus produce an alkaloid compound known as caffeine. Though it may seem strange, the purpose of caffeine is not to stimulate the human nervous system (though it is a wonderful side effect) but rather it is produced as a defense mechanism for the plant. Making this compound is a complex process that involves many metabolic steps within the tissues of the plant. There are certain factions out there who would like to argue that this is proof against evolution but, as always, evidence seems to be the downfall of their argument. 

Creationists will tell you that the adaptations we see throughout the living world are too complex to have happened by accident. In reality, there is a vast amount of evidence that disputes this. Caffeine is one such example. It has evolved independently multiple times in many different plant lineages. Looking at the genome of coffee, researchers at the University at Buffalo (my alma mater) found that the genes involved in the synthesis of caffeine did not arise all at once. Instead, the genes duplicated multiple times throughout the history of this genus with each duplication coding for another step in the process of producing the caffeine molecule. The interesting part is that each step of this evolutionary process produced a chemical that was itself useful to the plant. The precursor compounds are bitter and toxic to the kinds of animals that like to nibble on the plant. 

As it turns out, the benefits that the plants get from caffeine aren't restricted to defense either. Coffee, as well as other flowering plants such as citrus, produce small amounts of caffeine in their nectar. Researchers at Arizona State University found that bees were 3 times more likely to remember a flowers scent when there was caffeine in the nectar than if there wasn't. This serves a great benefit to the plant producing it because it means that its flowers are much more likely to get pollinated. As it turns out, humans aren't the only species that enjoys a good buzz from caffeine.

Before we get too excited over coffee, we must remember that is definitely has its downside. Worldwide, we humans drink roughly 2.25 billion cups of the stuff every day. In order to produce that much coffee, humans have turned somewhere around 11 million hectares of land into coffee plantations. This has come at an extreme cost to the environment. Also, being a tropical species, the types of habitat used to grow coffee were once lush, tropical rain forests. A majority of coffee consumed around the world is produced in monocultures. Where there once stood towering trees and a lush understory is now an open, chemically-laden field of coffee shrubs. There is hope, however, and it is rising in popularity. 

If you enjoy coffee as much as I do, you should certainly consider switching over to shade grown coffee. I have attached a fair amount of literature at the bottom of this post but the long story short of it is that growing coffee is much less harmful to the environment when it is grown in a forest rather than open plantations. The structural complexity of shade grown coffee farms allows a greater diversity of plant and animal species to coexist with one another. Species diversity and richness are significantly higher on shade grown farms than on open field plantations. 

So, there you have it. Coffee is as complex as it is interesting. We humans are simply lucky to have stumbled across a plant that interacts with our brain chemistry in wonderful ways. Certainly coffee has benefitted in the long run. 

Photo Credit: Ria Tan (

Further Reading:

Walking Palms

I don't know about you but Socratea exorrhiza has to be the strangest species of palm that I have ever laid eyes on. Native to Central and South America, its peculiarly stilted appearance has earned it the common name of "the walking palm." Whereas most palms invest in heavy trunks, the walking palm sends out a lanky set of stilt-roots upon which the palm grows like some otherworldly tripod.

There has been a lot of debate over the last few decades as to the purpose of these stilt-roots. In 1961 it was suggested that they were an adaptation for living in swampy areas. To date, no evidence of this has been found. Others have suggested that these roots are relatively cheap to produce compared to a solid trunk, thus allowing more investment in growing taller in a shorter amount of time while still maintaining structural integrity. This sounds attractive and is probably part of the puzzle. However, I feel that a particular study published in 1980 offers the best explanation.

Tropical forests are full of decomposition. The omnipresent threat of rot means there is a constant rain of limbs and snags from the canopy above. Trees regularly topple as well. For most plants, getting flattened by such debris is usually fatal. This is not necessarily so for the walking palm.

It has been observed that walking palms flattened by a fallen limb or tree can actually "walk" themselves out from underneath. Since most of the trunk is capable of producing stilt-roots, it doesn't take long for a new anchor to become established. Once this occurs, the palm is free to continue its journey into the canopy.

Getting squashed isn't the only worry either. Light is a premium in the deep shade of a rainforest understory. It is also short lived. A hole in the canopy that provided ample light one week may quickly close in the next, removing the life-giving rays of the sun. If a plant were able to "move around" it could potentially relocate to a sunnier spot. In a sense, this is what the walking palm does.

Walking palms are positively phototropic, meaning they lean towards a light source. Leaning can put stress on a trunk to the point that the tree topples over. The walking palm gets around this by sending down those stilt-roots, which provide support as it chases light through the canopy. In a sense, this palm "walks" itself around the forest in search of the best light. Whereas most trees are stuck where they germinate, the walking palm has, in a sense, freed itself from such restrictions. As such, older trees are often found far from their original germination point.

Once in a favorable location, the walking palm will right itself and continue upwards. At this point, the old trunk and roots are superfluous and will often rot away. For a young tree, this process can happen in as fast as two or three years. This is an incredible feat considering the time scale most trees operate on. Personally I would love to be able to observe a forest with walking palms over a few decades. Seeing how their positions change with time would be fascinating. At the very least, their bark is often covered in epiphytes, which offers a lot to comb over on our timescale.

Photo Credits: Hans Hillewaert (Wikimedia Commons) and John H. Bodley and Foley C. Benson (infographic)

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