It seems like it isn’t, they may not have a animal equivalent immune system but they must have something to avoid being overtaken by fungi or bacteria etc.
*Something I was told long ago to explain things like multi species grafts etc.
Just the fact that dead plants rot much more easily than live plants indicates that there must be some sort of immune system, even if it doesn’t much resemble the one in animals.
Yes, obviously, but what?
For one thing, plants have tough outer skins, especially the underground parts. But what else to they have to keep themselves from rotting alive? I’ve wondered about that too.
Wikipedia has a nice article on Plant disease resistance.
Based on the wikipedia article, my unschooled opinion is that they very much do have an immune system, even if they don’t have circulating immune cells.
That Wiki article informs us that plants have some degree of active immune system, and not just a totally passive immune system (as I had always assumed/imagined).
This blows me away to learn this. I never woulda thunk it. Serious iggorance fought here!
Plants have a complicated immune system. A lot of the important pathways (such as Toll) are pretty well conserved across multicellular eukaryotes.