If you live in America, depending on what state you live in, you get somewhere between 10-70 inches of rain a year. A desert, however, does not get 70 inches of rain … or 60 … or even 10. A desert is defined as an area that only gets less than 10 inches of rain a year. As you probably well know, a desert contains only those hardy organisms that will survive under such a scarcity of water. A North American desert is home to snakes, rocks, sand, beautiful sunsets, and a well-known, spiky plant called a cactus.
Cacti are perennial, which means they last for a seemingly endless amount of time. (Apparently this only applies to native cacti, because I successfully killed a personal one once.) I’m not sure about you, but I never really thought much about cacti. Because they survive in the harshest of climates, I had the cactus pegged in my mind as the mighty battleship of the plant world—aka indestructible. In reality, cacti are very tough, to say the least. But underneath their rough exterior is an extremely elaborate system that enables them to gracefully withstand the withering heat of the desert.
First off, cacti are actually succulents. I suppose this shouldn’t be too surprising, considering the fact that there are so many varieties and sizes of cacti. But if you’re like me, when you think of cacti, you mainly think of the tall ones with several arms pointing upwards from the elbows. In reality, there are over 2,000 species of cacti. One species in southwestern America can grow to be over 65 feet tall! To give you an idea of how tall that is, a standard telephone pole is about 40 feet tall.
In order to grow and survive, the cactus does need water—a difficult necessity in its natively arid climate. Cacti have a network of shallow roots that spread out widely underneath the plant. When the desert receives rain after an especially long period of drought, little bumps on the roots quickly develop into a net of tightly-knit, thin, whitish roots—kind of like a tight spider web. This net of roots allows the cactus to get every possible drop of water from the rare desert rain. After the rain, the webs of roots are discarded, but the bumpy bits remain, standing guard to perform their duty once the clouds open up again. Cactus roots also act like sensitive fingers; they can tell when the ground is getting too hot. When this happens, the roots contract, tugging the cactus deeper into the cooler ground below before damage is done.
The surface of the cactus is covered with shallow pits. Out of these pits grow many groups of spines, which are kind of like the leaves on a tree. Actually, the spines are literally transformed leaves. These leaves don’t perform photosynthesis for the cactus, though; photosynthesis in normal trees requires abundant water, and since the cactus doesn’t have this resource, its production process happens within the main part of the cactus. Because of this, the cactus’s “leaves” turn into hard, dry spines.
These spines prove very beneficial for the cactus. Most people (including me before researching for this article) think that cactus spines are mostly used for protection against animals. This is actually true. Herbivores do exist, and—believe it or not—eating cactus has many nutritional benefits, so the cactus has to have some protection against hungry critters. However, the cactus’s spines are mainly used in the water management field. When you wash your hair, it’s probably the last part of you that dries when you take a shower, right? The same is true for a cactus. Its spines are like your hairs; they hold in moisture and prolong the evaporation process on the cactus’s exterior.
As if these modified leaves don’t do enough already, cactus spines still have more to do in the H2O department. In order to get as much water as possible, the spines will spear droplets from occasional fog and move the moisture down towards the cactus’s roots. The ribs on a cactus perform a similar duty, expanding when it rains to trap precipitation between the creases. When the weather is hot, the folds close like an accordion to keep the moisture inside.
The outward appearance of a cactus plays a vital role as well. No matter their shape, cacti are designed to minimize sun exposure. Little, round cacti have very little surface area exposed to the sun, while tall cacti and prickly pear cacti only have their edges, tops or sides exposed to direct sunlight.
Because of their spiky guise, cacti can look pretty mean. But actually, they’re really a community player. Cactus flesh oozes sweet nectar that entices nearby ants. Because of this constant source of food, the ants set up camp at the base of the cactus and nest there. In return, the ants remove destructive predators like fungi and bacteria from the outside of the cactus, fertilize the soil with their waste, and carry cactus seeds to other areas.
Ants aren’t the only creatures that love cacti. So do bats. Bats love the nectar inside of the flowers on the cacti, but they have to be able to precisely pinpoint the location of the flower to avoid being impaled on the spikes all around. Some cacti have blooms that are firm and waxy, and when the bat calls in the air, the sound waves bounce off the flowers and return to the bat’s hyper-sensitive ears. With this use of sonar, the bat is able to precisely calculate the floral center and drink from the cactus blooms’ sweet syrup.
All of this is pretty surprising, huh? There’s a lot more to cactuses than just being spiky green blobs. When you look at nature, it is inspiring to see how everything works so well together, sometimes in surprising ways. There are many symbiotic relationships that are not obvious when you just take creation at face value. God created it all to work together in perfect harmony. In Isaiah 41:19, He said that He put the plants and trees that He created in the perfect environment for them. If He put this much thought and care into creating trees and plants and cactuses, consider how much time and love went into creating us!
Sure, the cactus is an interesting creation that has fascinating systems to keep it alive. But so are you! You are the greatest physical creation God can create! Think about all of the perfect processes going on inside your body right now. Think about your specialized environment—the things that occur in the world around you that are necessary to keep you alive. Human life requires a lot more than a cactus. And God created it all especially for you. What an awesome God we serve! Looking at His creation is one way we can make Him even more real to us—and even more grateful for the incredible mind that created the natural world to sustain us.