I am writing a book, and I want to create either a sentient fungoid or plant and I wish for it to use hormones instead of neurons to transfer information. I'm not sure how this would work and affect the capacities of the plant/fungoid?
It's possible, doable, and there is real world research on plant intelligence.
There are a few "problems" with this kind of intelligence, though. Comparative problems, having to do with speed.
Let us talk about something more basic than sentience. I think we can agree that consciousness is a prerequisite - you have to be aware before you can think "I am". We still know little about consciousness, but it's all about computing and how data is moved around a colletion of parts.
In our case, we use neurons. It may be that one day we will replace them with electronic parts. What neurons and electronics have in common is that they use electricity. For neurons, this means a signal can travel up to 120 meters per second (1 meter is about 1.1 yards, or a bit more than 3'3"). With electronics instead of neurons, an electrical impulse will move at a considerable fraction of the speed of light.
In very laysman terms, it means that if I step on your foot, the pain signal will reach your brain in really short time, and you will be able to react practically instantly.
A plant or a fungus, though, which can't rely on electrical impulses and must communicate solely through chemical signals... Well, that might take some time.
If I kick the ankle of your fungoid, its ankle will start to produce the chemicals that signal pain. Now it doesn't matter if it has a brain somewhere or if its processing elements are spread wide over its body, it will take a lot of time for its circulatory system to distribute those signaling chemicals to its "neural" network. For a human sized fungus monster, this could take from minutes to hours, depending on your design - but it could be faster if your creatures have a heart to pump their fluids.
Now, the signal doesn't just have to reach the "neural" network. Each element must process its input, and communicate its processing result to the elements connected to it, many times.
Your fungoid might start calling me names days after I've kicked it.
For a creature like this, a mobile lifestyle would be a no-no. It's no good moving around if you'll only react to the simplest obstacle in your path only on the next day.
Of course, this is all assuming that your creatures are human sized. If they are small, the distance the chemical signals will have to travel before a reaction can be taken will be shorter too. Remember, bacteria and protozoa have no neurons, and they react to their environment in reasonable time (usually - but not always).