I went to Gilly's class to discuss biomimicry and more importantly taking a closer look at the world. I finished my talk by giving every student in the class a piece of wheat grass and asking why they thought it was designed the way it was. They had some great and inventive answers, just a small reinder about how we loose the power of imagination and thinking outside the box as we age. But back to my topic, leaves are a great example of how form follows function.
A plants leaves serve the very important task of food production. They contain chloroplasts which use the power of sunlight to turn water H2O into oxygen O2 via photosynthesis. This process can get infinitely more complicated depending on the type of plant, but for today we will keep it simple and just do the process and structure of an average leafy plant. The leaves also transpire i.e. let gases and even water escape via leaves.
Now this diagram shows the structure for an average leaf, but each of the above sections can be expanded or condensed based on the plants environment. Cacti have modified leaves in the form of spines, I assure you these really are their form of leaves. They have condensed the leaf volume down drastically because they live in an volatile sun and heat environment. They also have developed a very thick waxy cuticle to literally seal in water and prevent transpiration.
So compare the succulents with their complete opposite, plants on the jungle floor, like the Swiss cheese plant (Monstera deliciosa). This is a plant with giant dark green leaves. So why have huge wide leaves? Well this plant normally lives on the jungle floor where only traces on sunlight sneak through the dense canopy. The most efficient way to get enough sunlight is to cover as much area as possible. Jungles are also subject to high rain volume and humidity, so large leaves allow excessive water to transpire, but humidity doesn't allow the plant to become dehydrated.
For the last plant today, lets look at one of the worlds most popular plants, a rose. Roses typically like moderate sun and light watering. They are notoriously hardy and easy to maintain. Their leaves are smaller and moderate in amount. This makes sense, have leaves that are a conservative size because they happily exist in open sun areas. They do not need to be ultraconservative to survive extreme temperatures so the conventional leaf shape is still acceptable. They have a drier leaf because they do live in direct sunlight and lower humidity areas. they can't afford to let too much water transpire.
I hope taking a look at three types of leaves inspires you to take a closer look at plants and life on this planet in general. Nature designed everything with a purpose. Use your inquisitive brain and take a deeper look and ask why.
That's it for now,