When do mushrooms release spores

The paler ink is from Coprinus comatus. Question : Why does the cap dissolve and drip away? Answer : To help spore dispersal. The densely packed gills of Coprinus comatus are parallel-sided, rather than with a V-shaped cross-section, and without the strict vertical control of gills that is found in the bulk of mushrooms. This would seem to make effective spore dispersal very difficult.

However, Coprinus comatus has overcome these difficulties and the following diagram in the same style as the earlier diagrams shows the process. Figure 1 shows parts of two neighbouring Coprinus comatus gills, in stylized cross-sections. Unlike the great majority of mushrooms the spores of Coprinus comatus mature in a regimented way.

The spores near the lower edge of the gill mature first. The spores are colourless when immature but then pass through various shades of pink and brown to become black at maturity. Figure 1 shows this, with the lowest basidia bearing black spores and a lightening of spore colour as you look up the length of a gill - reflecting differing stages towards maturity. The mature spores that were shown in figure 1 are ejected by the water-drop mechanism and figure 2 shows the spore trajectories.

At the same time the spores in the next band of basidia are now mature. You can see that the spores that were dark brown in figure 1 are now black - and there have been other colour changes in the spores higher up. Figure 2 also shows the lower edges of the gills beginning to dissolve into an inky mess which drips away.

In figure 3 more of each gill including the basidia which shot off their spores in figure 2 has disappeared as ink drops and now the second band of basidia is releasing its spores. This process continues, the spores maturing in rising bands and the gills dissolving and dripping away below the bands of maturing spores.

Each group of mature spores therefore has only a very short distance to fall, before being clear of the ever-diminishing cap and so the lack of V-shaped gills is no hindrance to spore dispersal. The absence of V-shaped, vertically oriented gills does not, in any way, make Coprinus comatus an "inefficient" mushroom.

It is a prolific producer and disperser of spores, and has simply evolved a different and effective solution to the problem of spore dispersal. The members of the genus Coprinus are commonly called Inkcaps, because the caps dissolve into an inky mess and drip away.

The caps of many of the other Coprinus species do not dissolve quite as dramatically and with such copious ink as those of Coprinus comatus. Moreover, Coprinus comatus produces the largest mushrooms in the genus, with most Coprinus species producing mushrooms with caps no more than two to three centimetres tall.

The bulk of what was said above was devoted to describing "what" happens during spore release. This section discusses some of the basic physics involved in the "surface tension catapult" mechanism that has already been described. It adds nothing new to "what" happens but briefly explains "how" it happens. As the drop expands, its surface area increases and so does the total surface energy arising from surface tension. When the drop comes into contact with the film of water, the drop collapses, with the water from the drop flowing into the watery film.

That action reduces the total surface area of the water - and so also the total surface energy. Conservation of energy is a fundamental law of physics. Energy never disappears, though it may be transformed from one form into another. So, if you start with a certain amount of energy you must end up with the same total amount - though it may appear in different forms. During the spore launch, while the total surface energy is reduced, the spore and its watery coating gain kinetic energy and momentum.

Basic physics indicates that some of the original surface energy would be transformed into heat - though how much, is unknown. The sterigma also plays an important role in ballistospore discharge.

Throughout the process the sterigma maintains its shape by internal turgor pressure. The sterigma therefore provides a rigid launching platform for the spore and is able to absorb the recoil from the accelerating spore, with only very minor deformation.

Without that rigidity, energy would be wasted in deformation of a laxer sterigma - so leaving less energy to contribute to spore acceleration. In an analogous way, you can jump higher if you launch yourself from solid ground - rather than from a much more compressible surface.

The discharge mechanism Now it is a simple matter to explain the way in which the spore gets off the gill and away from the mushroom cap. After discharge - getting the spores further away While the spore leaves the basidium with a tremendous acceleration, it is small and quickly feels the effects of air resistance. More about mushroom growth - and other ballistosporic basidiomycetes In the bulk of mushroom species the spores in different parts of a gill may mature at the same time.

The Inkcap mushrooms Coprinus comatus , a common and widespread mushroom-producing fungus, is commonly called the Shaggy Inkcap, because the mushroom cap has prominent white to pale brownish scales that stick out from the cap giving it a shaggy appearance and the cap dissolves into an inky mess and drips away.

Many fungi need two of these colonies to grow next to each other and to mate before that fungus is able to form any new spores and so spread further. Fungi need to produce so many spores because most spores simply die where they land, lacking water and food.

Some fungal colonies can grow for a very long time and over a very large area. Many fungi form a fruitbody shaped as a mushroom, a shelf-like bracket, a puffball, a coral or simply like a splash of paint. The main purpose of the fruitbody is to produce spores so that the fungus can spread. Spores of mushrooms form on special hyphae on the surface of thin gills that form in a circle hanging on the underside of the cap. The cap has a curved shape poroharore so that the rain droplets run off and the spores keep dry.

Mushrooms must shed their spores fast as both mushrooms and spores often live for only a few days. If you use a microscope to make the spores look much larger, you can see them clearly. Check out the spore print activity to learn how to make a print from spores of a mushroom. Using microscopes to identify fungi parts — adapt our Ferns under the microscope activity so students can have a closer look at different fungi — and why not build in some additional learning about How microscopes magnify?

Mushroom spores — learn how to make a print from spores of a mushroom. The Science Learning Hub would like to acknowledge Manaaki Whenua — Landcare Research and the writers for their permission and help to adapt this publication for the web.

In some species of cup fungi there is a little lid at the top of the ascus which is forced open to allow the spores out. In others the tip of the ascus ruptures more irregularly.

The spores may be shot several centimetres up into the air and, as in the case of the mushroom, air currents carry the spores further afield. From the structure of a cup fungus, you will realise that many asci can simultaneously shoot their spores. Often when you pick up fresh cup fungi the mechanical disturbance of picking up a specimen is enough to jolt thousands of mature asci into releasing their spores and, if you are attentive, you will see a small cloud of spores arising from the fungal surface.

As well as the simple cup fungi, the "compound" or "distorted" cup fungi such as Cyttaria , Morchella and Leotia release their spores in the same way. Many, but by no means all, of the flask fungi release their spores actively.

Flask fungi differ fundamentally from the cup fungi. In the latter the asci line the surface of an open cup or disk but in the flask fungi the asci are contained within a chamber that has only a narrow opening at the top.

So there is no mass firing of asci. Instead, when an ascus is mature its tip extends to the opening, shoots out its spores and then collapses back into the chamber. Then another ascus can have its turn and so on. The flask fungi also get a mention in the passive release section below. A mature puffball is typically a flexibly-walled, apically open sack of spores. A raindrop or foot hitting the sack momentarily compresses the air inside thereby forcing a puff of spores through the apical hole and several centimetres into the air.

You can see this for yourself if you flick a puffball with your finger. While some sort of impact triggers the initial release of the spores from the fruiting body, wind takes over as the agent of longer distance dispersal. Earthstars release their spores in the same way as puffballs. Amongst the other puffball relatives the tough skin of Scleroderma splits to expose the spores to wind and water, allowing the spores to be washed or blown away.

In both Calvatia and Pisolithus the fragile outer skin breaks away to, once again, allow wind and water to disperse the spores. Pisolithus has an interesting internal structure. In this photo of the cross section you'll see that the inside is full of what look like yellow to brown rice grains. Initially there are basidia in each of those grains or peridioles.