Moss is an interesting type of plant and is fairly old, evolutionary speaking. In a development ranking, moss would place between algae and ferns. You might be wondering right now what that has to do with anything. Well, if you ever looked at leaves on trees (or ferns, for that matter) and saw the veins, you would see how they are like the veins in our bodies. That is part of the vascular tissue of the tree that connects all the way from the roots to the leaves to send water up and food down. Since moss does not have vascular tissue, it cannot transmit water and nutrients as far or have the structure to stand as tall, so it stays smaller.
You might have also noticed that moss grows on rocks, logs, and the flare at the base of trees. It just so happens that these mosses need moist places with less wind to evaporate their water. Why is that? Have you ever laid on the beach or in a field and found that the wind gets calmer closer to the ground? Well, so has moss, which is another reason why they are so small. Furthermore, the moss doesn’t just need that moisture to feed itself, it also needs it to reproduce. Moss doesn’t use pollen but has swimmers that are not very strong and short lived as they cross water droplets from the male shoot to the female shoot to reach its egg.
Occasionally you may see these stems sticking out of the tips of the green moss. Those are the sporophytes (which are the result of the fertilized egg) getting ready to release their spores to be carried on the wind…. But wait, these mosses don’t like wind. Right! And that’s why the sporophyte sticks out above the moss, to break the boundary layer and reach more wind. These spores carried on the wind will land somewhere and hopefully grow to be either male or female shoots.
Now, piecing this all together, moss is like a miniature forest with its own little climate and ecology of microorganisms living in it. With a field microscope or hand lens, anyone can inspect this forest, find its creatures, and see the structure of the shoots designed to capture moisture. Try it!
If you liked this short note on moss, consider the book “Gathering Moss,” by Robin Wall Kimmerer.