On biblical Day 1 the Creator got light and dark organized, on Day 2 He dealt with water and dry land. Then, on Day 3, He went to work with the old green thumb.
So describe a leaf. Flat, green, sticks out of a stems or branch? If the plant’s big enough we pull up a lawn chair to enjoy the shade. If it’s munchy we head for the kitchen to cook.
Technically a leaf is any flat, green outgrowth from a plant stem. It absorbs sunlight and manufactures plant food. Pine needles, blackberry thorns, and bean tendrils count as leaves. The presence of the yellow-green element chlorine in the pigment chlorophyll gives plant leaves (and stems) their characteristic color.
Chlorophyll is a chemical bathing beauty that absorbs sunlight but never gets tan. Picture a fetching magnesium ball inside a nitrogen-filled ring strutting about on stiletto heels while switching a sexy tail of carbon and hydrogen molecules.
The stuff fuels photosynthesis, the process of using light energy to decompose water then mix in carbon dioxide gas, and “Voilà, mes amis, les carbohydrates!” or chemical energy, a sugary delight plants love.
Science teachers used to say cells had a wall, a nucleus, and “protoplasm” or undefined oozy stuff. Later, electron microscopes showed cells contain complex tiny organs that do all kinds of work, and plant tissues are like chocolate chip cookie dough sandwiching bumpy green organelles called chloroplasts.
A chloroplast lump is maybe a thousandth of a millimeter thick. Let’s say a meter is about a yard. Divide that into a thousand parts, then divide one of those into a thousand more parts, and you get an idea why it took an electron microscope to see chloroplasts.
The teeny weeny chloroplast wears a two-layer coat: (1) its lamella, an oh-so-thin plate of tightly stacked, teenier weenier hollow disks that insist we call them thylakoids, and (2) its stroma, a tissue chock full of dissolved enzymes which are REALLY small.
The disks manufacture a substance, called in shorthand ATP, that works with the dissolved enzymes to store and move photosynthesized sugars around the plant so it can grow and reproduce.
How do we recognize a plant on skid row? Easy, in the middle of the growing season the leaves pale and eventually look bleached out. This results from the failure of chlorophyll to develop, so the leaves can’t capture light and can’t make a meal. The plant is starving. The culprit may be old age, malnutrition, thirst, disease, bad weather, hungry bugs or a host of other problems.
As Kermit the Frog once lamented, “It’s not easy being green.”
Contact Noelle M. Hood at [email protected].
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