This week we’re talking about roots and at first I thought about not taking it quite literally but then decided that the biologist in me wanted to be more botanist and I wanted to delve into roots themselves. Now, I’ve had a plethora of biology classes in my life and as with all things we learn, if we don’t use it, we lose it. Of course the basics are still there in our brains and we understand the premise of how things work but we tend to forget the tiny details.
So, off I went to the internet and did some refresher research. I happily had a white icicle radish to diagram. Now, I’ll be upfront, I only briefly diagrammed the radish above. There’s so much more to the cells and vascular life of a plant but that’s beyond the scope of this blog, but I hope this will at least educate you a little bit more about the plants you are growing.
Despite being below ground, roots are very important to the life of the plant. Often if you transplant your seedlings improperly or you damage a root when un-potting it to put into the ground, sometimes your plant just won’t recover. Roots are the anchor to the plant, they absorb water and minerals, may store food, and act as a transport system for nutrients to traverse from the stem of the plant down to the roots and vice-versa .
You’ve got your seeds in the ground, you’ve watered them in and now you wait for germination. The first thing that comes out of the seed is the radicle. This is the primary root and then depending on the plant you are growing, will eventually become the main root, the tap root, in root vegetables like carrots and radishes.
I’m using a tap root only because it is easy to diagram and to explain—and again, I had it on hand. But the other main system is the fibrous root system which is common in monocots like grasses. In this system the main tap root fades away and the adventitious, fibrous roots are what is left.
So, above ground is the leaf system which is constantly photosynthesizing light energy into chemical energy for the plant to utilize and grow. Since that is a different topic entirely I’m going to abstain from delving into that more.
On the outside of the root is the epidermis, which like the epidermis of your own skin, acts as the protective barrier for all of the cells on the inside of the root tissue. It’s a protective coating but also absorbs water and nutrients too. From the epidermis arise the root hairs which also act as another method of increasing surface area for absorption. Like their length, they are short-lived. The diagram doesn’t accurately show a root hair, I’m really pointing to more, smaller lateral roots, but for the sake of understanding that root hairs are smaller than the general root I pointed to the smaller roots. Micrometers in size, this is the type of thing you could see with a good macro lens or a microscope, or maybe with really good eyesight.
Lateral roots are just more roots extending from the main tap root, serving as extra support and uptake of nutrients from the soil. The root cap serves as a protective layer as the plant moves through the soil. The cells of the root cap are consistently being sloughed off and new cells are constantly being added. This link suggests that when the root cap is displaced and has not had time to regrow, that the roots of the plant can grow awkwardly, not in their typical downward motion, speculating that perhaps the root cap also functions as a sensory receptor of gravity in some way. I have not researched more into this but the idea is interesting.
Right above the root cap is the root apical meristem, the active, cell dividing section of the plant. These are undifferentiated cells (stem cells are probably a term you would know), they are cells that can become anything in the plant. The opposite of a root apical meristem would be the growing tip on the shoot of a plant.
I dug through some of my older photos of epiphytic roots of orchids so I could show those as well. Many people are unfamiliar with epiphytes and their roots, mistakenly calling them parasites. While there are parasitic plants (see: dodder, indian pipes, beech drops, mistletoe, and squaw root as examples), epiphytes only utilize the other host plant to latch on and grow, not taking in nutrients from the host plant.
The photo above is a cattleya we bought at a big-box store. These are often potted up in spaghnum moss or orchid bark but we opted to put them in a hollowed out coconut (found commonly in south Florida when we lived there). After several years the roots had grown completely over the coconut.
Another epiphytic orchid is the ghost orchid, Dendrophylax lindenii. This one happens to also be a leafless orchid and subsequently also conducts photosynthesis via its root system. We’ve seen some crazy root masses on ghost orchids sometimes making it impossible to tell if it is one plant or multiple plants.
I could write more and more about roots but there are more informed places to dive further into the topic if you are so inclined. Here are some helpful links:
+Plant Anatomy from the University of Illinois at Chicacgo
+Root Anatomy from the University of the Western Cape
+Root System information via National Institute of Open Schooling in India (thought that was interesting, but probably one of the most interesting links).
I hope you now know a little bit more about the roots system of the plants you grow and take a few minutes to click through and read a little bit more.