Plasmodesmata: How Plants are Actually Single Cellular Organisms

You read the title right. Plants only have one cell, technically. You may be thinking back to high school biology and wondering how that’s possible! You studied the plant cell! They have cell walls and stuff.

True. But consider this; how are plants supposed to share sugar and water and stuff between their cells when each is imprisoned inside a shell of impenetrable cellulose? How do root cells get glucose from the leaf cells, and how do they get water from the root cells? 

Yes, yes, plants do have tubes which transport water and sugar rich sap through their bodies called phloem and xylem ¹great word for using X and Y in Scrabble by the way, 17 points!. Similar to our blood vessels. (technically only vascular plants have these. Mosses, hornworts, and liverworts do not have xylem, phloem, or any true vascular structures). But that doesn’t answer how the stuff actually gets *into* the cell. We animals don’t need to worry since our cells have permeable membranes, but plant cells are way more isolated. 

Plasmodesma:

The answer is that there are special holes in the cell walls called the “pit” that let things cross over ² very impressive scientific terminology, I know. A whole 5 points! . Most of these “pits” are just areas where the cell wall is much thinner, stuff still has to diffuse through the membrane.

But some pits have what is known as a plasmodesma (plural form is plasmodesmata). It’s like a tubular bridge between the two cells’ membranes which allows molecules and stuff to travel from one cell to the next without ever crossing a membrane. Ever see a space-time diagram of a wormhole? It looks like that, but more “plant-y”. ³Unfortunately, planty is not a viable Scrabble word.

There are also special protein structures around the plasmodesma that can squeeze it closed to prevent water or pathogens from getting through.

Plasmodesmata form when cells are first dividing. At the point where the two membranes should fully split, it doesn’t. A tiny bit is left unsplit. There are also ways of forming new plasmodesmata between cells other than this, however.

Every single cell in a plant’s body is connected to every other through this system of plasmodesmata. This means that a plant only has one giant continuous membrane that is shared by all its cells. Plant cells also share their cytoplasm. Hence scientists call this “synplasm”, because I guess “shared cytoplasm” takes too long to say. Which means that plants are technically just one giant cell with a lot of compartmentalization. Kinda like how an office full of cubicles in it is still just a big room with a lot of dividing walls in it.

Conclusion

Do scientists really define plants as single cellular? Not really. Like, that’s kinda silly. Even if they’re technically a single cell, they function as multicellular. But I still think it’s pretty cool trivia. And just imagine when you rock up to that scrabble board and whip out a word like PLASMODESMATA like a heckin’ badass, 24 points!

For more about plants, check out my other planty posts! You know about Ginkgo trees? Wanna know how they actually suck? Or do you want to know about my evil plan to use salt tolerant plants to conquer California? If you’re somehow not interested in that, that post also contains an explanation of how its is that some plants can be salt tolerant.