OF WAX AND WATER

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Submitted Date 10/19/2019
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This time of year, craft fairs spring up like wildflowers. Loads of locals display their carefully-fashioned wares in the hope of catching a pre-season Christmas shopper's eye. As someone who dabbles in a craft or two, I can appreciate the work that goes into some of these items. Metal casting jewelry smiths create delicate dangles I can't imagine making myself. An oil painting or two will catch my eye and I marvel at the skill and imagination behind the brushstrokes. Lawn ornaments welded out of rebar aren't really my style, but I bet making them is sweaty work. Most craft fairs feature the staples of the home crafting trade; a booth of soaps, a "vintage" clothing stand, crocheted hats and scarves. I keep a casual pace as I stroll among the offerings. I pause when something unique catches my eye.

It was something unique that caught my eye last year at a fair in Atlanta. An enterprising artist had pressed flat the leaves of a magnolia tree. Using what I expect was a very sharp needle and a very tiny hook, she turned them into elaborate sculptures and delicate artwork. They are truly incredible to lay eyes on. The cogs and wheels in my head start to churn overtime when I see creations that stand out this way. How did they make them? What process did they use? What things did they try that didn't quite work? I imagine myself trying to duplicate the effort.

It's no wonder the artist, whose name is Susanna Bauer, chose to use magnolia leaves as a medium. They're thick, leathery and quite durable. Anyone who's lived in the south is familiar with the magnolia's fragrant white blooms and the leaves' glossy shine. That shine comes from the leaves' waxy cuticle, a rain-resistant coating the plant produces as protection. This icon of the American South isn't the only leafy lifeform that uses this defense. Plants in very arid climates and plants in tropical environments have both evolved a waxy coating, but for different reasons.

Although we can't see them with the naked eye, the leaves of most plants have tiny holes in them called stomata. These are how the plant "breathes" or takes in oxygen and releases carbon dioxide. Moisture, on the other hand, is absorbed through the roots. This is why drip irrigation is more effective than spray irrigation and why you should water your garden close to the ground. Leaves don't take in water, only gases like air.

Think about what happens when oil is dripped into a bowl of water. The two liquids separate into different layers. The waxy cuticle of plants is made of lipids - or fats - that repel water. But wait, plants like water, right? Why would they develop ways to repel it? There are two very good reasons. Plants that live in desert conditions, with very little available water, want to hang onto what moisture they can get. Having a waxy layer on their surface helps to keep water from evaporating and escaping the stomata. It can also serve to bead water up on the surface of a leaf that will then trickle down to the ground and be absorbed by the roots.

In contrast to the desert, plant life abounds in the tropics. The abundance of water encourages plants to grow on nearly every surface. Many of them also have the same waxy cuticle on their leaves. So why, in such a dramatically different climate from the desert, do some plants have the same adaptation? Water resting on a leaf surface can cause problems. Because plants get their energy from the sun, it's important that light isn't blocked from reaching the leaves. Drops of water bend and refract the light, changing its qualities. Non-plant life forms, namely fungi, like water too. Aside from interrupting light absorption, many fungi are plant pathogens. Water on the leaves may encourage harmful fungi to grow there, which can penetrate the leaves and hurt the plant.

The waxy, water-repelling plant cuticle on both desert and tropical plants serves another purpose. It acts as a barrier to predation. Some insects that feed on plants can't penetrate the leaves' coating and fly off to find another, less waxy victim. Not every plant has a waxy cuticle and some plants have thicker or differently-textured coatings to keep them safe. The desert and the rainforest are two extreme environments. They make good examples, but they aren't the only places where waxy plants grow.

The American South isn't exactly the Peruvian Amazon, but it is often hot and muggy. We certainly have molds and insects to spare. That's likely why the species of Magnolia that grow down here are so thick and shiny. The other trees and grasses, shrubs and herbs have their own ways of dealing with the southern climate. Some are adapted to have smaller leaves, some have spines, and some use biochemistry to keep cool. There's so much beauty and variation in a simple leaf, that it's no wonder artists are inspired by nature.

 

Read on with your bad self:

Magnolia Leaf art (Susanna Bauer)

http://www.susannabauer.com/

Southern Magnolia (Yale Nature Walk)

https://naturewalk.yale.edu/trees/magnoliaceae/magnolia-grandiflora/southern-magnolia-58

Leaves (Lumen)

https://courses.lumenlearning.com/boundless-biology/chapter/leaves/

The Formation and Function of Plant Cuticles (American Society of Plant Biologists)

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3762664/

Benefits of Drip Irrigation (Gardening Know How)

https://blog.gardeningknowhow.com/trends/benefits-of-drip-irrigation/

The Complete Guide to Magnolia Trees (Southern Living)

https://www.southernliving.com/home-garden/gardens/magnolia-trees




 

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