Leaving triffids alone they can spread out and be quite the problem in a couple of days. On the surface though their spawn rate is somewhat slow however it gets more dangerous when you go below. One walls will form and disappear randomly; two their are creeper hubs which spawn infinite amount of creeper vines in the area VERY quickly(all creepers die if a hub dies). And at the heart it’s a constant stream.
Fungaloids though have an exponential growth as one will make two more which make more continuing.
Ants actually fun fact can’t spawn fast enough to properly fight fungal infestations (Mycus mutation tree makes mince meat out of everything netting you allies and killing enemies).
Ants after some testing have a linear growth which kinda surprised me but they have a stupidly high growth rate (spawn rate stays the same, but number increases). The other two that act like this (triffids and Mycus) have a growth that changes. Triffids have triggers for growth spikes these are: Mycus incursion, Player attacks into the hive(colony?), and high death tolls(if alot die this cause a growth surge from what I can tell). Mycus grow exponentially permanently as they gain more units that produce spores which can produce more units ad infinitum. Mycus also gain steam from infecting other beings: players, NPCs, insects, and zombies.