Updated: Aug 9, 2019
Have you ever wondered why turf grass grows but never makes flowers? Or how it is able to keep growing even when you have cut it over and over again? It all comes down to a single word, “Meristem.”
What is a meristem? It is a small group of “undifferentiated cells” which simply means they haven’t yet received a responsibility of the type of cell they will become. For example, you have eyeball cells, skin cells, liver cells, and heart cells. Plants have root cells, leaf cells, flower cells, etc. So meristematic cells just haven’t become a “type” of cell yet.
So, what do they do? Much like stem cells in humans, their primary role is to divide and then they have the potential to become any kind of cell. In plants, these cells are only found in a few places, and usually at an apex or “peak” and thus their name is determined by their location. For example, a root apical meristem is where un-dividing cells grow and elongate in the roots. A stem apical meristem creates leaves on the stem, and a floral apical meristem, is what allows flowers to grow near the top or ends of plants. An artichoke is a good example of an apical meristem. The leaves seem to continue to grow in a circle forever and ever inside—unless…. you stop and pull those leaves off one by one. What do you find at the center? A tiny mound of cells you’d be lucky to see with the naked eye! This mound is what continually makes all those leaves, which in turn grow to be big and strong. That mound—is a meristem. Meristematic cells divide and make more cells which eventually become differentiated, or in other words cell “types”.
You can pull the leaves off of any plant, and it will be the same—an almost seemingly endless cutting away of leaves that just get smaller and smaller. In another sense you can even call meristems a type of motherboard for plant function because they communicate where the leaf will grow, or what the surrounding undifferentiated cells will become. So how does this fit into the bigger picture of plant growth?
When a seed is planted there are two meristems that start to work right away: Root apical meristems and stem apical meristems. As the plant is still in its “baby” stages it focuses just on getting nutrition, sunlight, good water, and growing bigger. In a sense, the plant needs to test its surroundings and has a limited time to do so—if it’s a healthy environment, or if it needs time to collect the resources it needs to start producing flowers and seeds the plant works until it is ready. When the time comes, a transition will help, much like adolescent teenagers, and the stem will shoot up. This is also called “bolting”. As soon as the stem has bolted, the leaves will start to get harder/less soft, and the plant will focus all of its energy on producing flowers and seeds. It has reached its reproductive stage.
So why does sports turf never flower? Why do floral meristems never form? How is it that grass can just keep growing?
Well it turns out that a plant meristem never stops growing until a transition happens, or it's killed. If the transition from growth to flowers doesn’t occur, then the plant will continue to grow leaves. This is how your grass keeps growing, and why it never flowers. When it is cut, it's like getting a haircut, but because it hasn’t had time to bolt to its flowering reproductive stage, it will go back to simply growing leaves. Want to hear a fun fact? When you allow your grass it bolt, It will grow flowers. Those flowers will grow seeds, and that is how most grains are formed. Corn, wheat, rye, barley, rice? —All grasses. You probably don’t want your beautiful turf to look like weeds though, so we recommend keeping it on a mowing schedule.