Feasibility of Giant Fungi

Question

I have a temperate rainforest environment within the arctic circle of my planet. What is the feasibility of fungi storing nutrients from dead matter during the daylight hours, then erupting to create a very tall (10-20 ft. ) cap & stem/fruiting body? I'm asking because I know fungi used to get rather large in the past, with the primary example being prototaxites.

Edit: This would not happen over night but over the course of a month or several weeks!

Thanks for the help guys, y'all have given me alot of factors to help support my fungi in a realistic environment.

Answer 1

Dispersal.

Your fungi are understory / soil saprophytes. Above them it is a thick and tangled mass of vegetation in the polar summer. No wind penetrates. If a spore is going to have a chance to find a new area suitable for growth (and not be outcompeted by its parent) it must move some distance from its parent.

Plants have this problem all the time: how to get the seed somewhere new. They have all sorts of solutions. I am not entirely clear why this is less problematic for fungi (spores are so small?) or maybe I just do not know about fungal evolutionary adaptions for this.

In any case: your fungus. If spores are released close to the ground they will land close to the parent. The higher they are released the better the chance for a breeze.

So the spore body grows, up past the plant life, pushing it aside. It grows fast, in a day or two, because it is mostly nonorganic. This spore body is largely water filled erectile tissue and maybe even gas-filled spaces - it needs to get big fast and long term sturdiness (like a plant with a place in the sun) is of no concern. The parent fungus has considerable water at its disposal and it pumps this into the spore body. This is unlike the sturdy prototaxites which did apparently persist for growth seasons, putting down growth rings like trees.

Once the tip of the fruiting body is above the mass of plants it explosively pumps its spores into the air from the tip, and collapses.

*re dead matter during daylight hours - fungi use the night time too. Rot never sleeps.

Answer 2

The best answer we can give you is it depends on the enviroment.

Is there any evolutionary push towards such sizes? In other words, would a fungus with such a large fuitbody tend to be more successful in its environment than another specimen with a smaller one?

And will this size be sustainable? That is, will there be enough dead matter for it to grow? Is the fungus free of the threat of animals eating its fruitbody? Can the fungus outcompete other fungi species, as well as microorganisms and carrion eaters for example, for access to nutrients?

If the answer is yes, then it is feasible. If no, then... As the creator of your world, it is up to you to decide.

It was just like that on our own planet. Prototaxites evolved and lived on Earth for a while because their form was positively selected - then the environment changed and they went extinct. The same is true for any other lifeform.

Answer 3

One way i could think of this working is that the mushroom's grow in swamps, where dead matter is laden within, or that the rainforest is heavily rich in nutrients within the soil. Maybe the mushrooms are feeding off of roots of the rainforest trees or root vegetable-like organisms in the ground, sort of like parasitic mushrooms do. For it becoming really big, the stem could be reinforced to hold such a large cap, but since prototaxites managed to grow as big as they did, this shouldn't be a problem.

Obviously you could just say that the mushrooms can grow to large proportions through some other new method, but that is just my two cents on the matter.