Fungus Fact Friday

Tagged: ecology

#054: Oomycota (Water Molds and Downy Mildews) 1

Fungus Fact / That's Not A Fungus!

#054: Oomycota (Water Molds and Downy Mildews)

The Oomycota (literally “egg fungi”) are remarkable organisms because they mimic fungi on a cellular level. They are heterotrophic (get energy from their surroundings) organisms, exhibit filamentous growth, digest their substrate before absorbing it, and produce sexual and asexual spores.  For these reasons, the Oomycota were once classified as fungi.  They have since been removed from Kingdom Fungi and placed in Kingdom Protista, Chromista, Straminopila, or whatever name it’s going by today.  That means it is most closely related to diatoms and brown algae (like kelp).  At first this does not seem like a logical grouping because most of these organisms are autotrophic (make their own food).  However, there are a few characteristics of the Oomycota that make them more similar to protists than to fungi.  For one, the Oomycota have cell walls composed of cellulose, glycan, and similar molecules.  Second, they primarily live as diploids (two copies of each...

#049: Coffee Rust [Archived] 1

Archived

#049: Coffee Rust [Archived]

Note: This is an archived post. You can find the current version of this post here. Coffee Rust (la roya in Spanish) is a disease of coffee plants that is caused by the fungus Hemileia vastatrix. If you enjoy a fine cup of coffee, then this is one fungus you should be very interested in.  The Coffee Rust is currently ravaging coffee trees in Central America, where 60% to 75% of the region’s crops are infected with the pathogen.  The result of this has been a 15% drop in Central America’s coffee output and a corresponding loss of more than 100,000 jobs over the last two years.  The high-end Arabica trees are particularly susceptible to the disease.  America’s major coffee producers have been able to find enough coffee to meet demand without a noticeable impact on price*, but smaller, specialty brewers are having a harder time.  And we haven’t seen...

#047: Mushroom Morphology: Truffles 1

Fungus Fact

#047: Mushroom Morphology: Truffles

Truffles are ascomycetes that form below-ground (hypogeous) fruiting bodies. These mushrooms look like small, lumpy potatoes on the outside.  When cut open, truffles have a marbled appearance.  Like the false truffles and sequestrate basidiomycetes, true truffles have evolved to retain moisture in arid climates or other harsh conditions.  Truffles evolved from cup-shaped ascomycetes with a spore surface exposed to the air.  To keep the spores moist, the cup became closed.  Eventually, the interior surface became wrinkled and condensed, creating the marbled interior.  There are a number of truffle species that exhibit various stages along this evolutionary path.  Many of these truffles are hollow on the inside, as the gleba (interior, spore-producing tissue) has not fully become compacted.  All truffles rely on animals – usually small mammals – to dig up the fruiting bodies and eat them.  Truffles attract these animals by producing various scents.  These scents are what give edible...

#046: Mushroom Morphology: False Truffles 1

Fungus Fact

#046: Mushroom Morphology: False Truffles

False truffles are basidiomycetes that produce fruiting bodies at or below the soil surface (hypogeous). These mushrooms are included in the gasteromycetes because they develop their spores internally and have lost the ability to forcibly discharge their spores.  Like the true truffles, false truffles disperse their spores by attracting animals like insects, rodents, and deer.  False truffles secrete scents to attract these animals, which eat the mushrooms and spread the spores around in their feces.  Most false truffles have a gleba (the internal, spore-producing tissue) that is divided up into small chambers called locules.  Many false truffles also have a short stipe at the base or a stipe-columella that extends into the gleba as a branching structure.  Aside from the stipe-columella, the gleba of false truffles is fairly regular in appearance.  This easily separates them from true truffles, which appear marbled when sliced in half.

#043: Mushroom Morphology: Bird’s Nest Fungi 2

Fungus Fact

#043: Mushroom Morphology: Bird’s Nest Fungi

These small (< 1.5cm) fungi are easily recognizable by their striking resemblance to a bird’s nest with eggs inside. The “eggs” are actually spore-containing sacks called peridioles.  As in the other gasteromycetes, the bird’s nest fungi produce spores internally and have lost the ability to forcibly discharge their spores.  To overcome this obstacle, the bird’s nest fungi developed their unique morphology to act as a splash cup.  The basic splash cup mechanism works as follows: a raindrop falls into the cup, which propels one of the peridioles (“eggs”) out of the cup.  The next challenge for the bird’s nest fungi is to stick to whatever they land on.  These fungi have evolved two different mechanisms in order to accomplish this.  Fungi in the genera Mycocalia, Nidula, and Nidularia have peridioles that are covered in sticky mucilage, which allows them to adhere to surfaces on contact.  Fungi in the genera Crucibulum...

#042: Mushroom Morphology: Earthballs 2

Fungus Fact

#042: Mushroom Morphology: Earthballs

This group of mushrooms goes by a variety of common names, including “earthballs,” “earth balls,” and “false puffballs.” Additionally, all of these mushrooms belong to the family Sclerodermataceae and could casually be referred to as “sclerodermas.”*  Using these terms to distinguish earthballs from puffballs is a fairly recent development, so many earthballs are still commonly called puffballs.  Visually, immature earth balls can look similar to puffballs.  If you are collecting puffballs to eat, make sure you know how to tell the difference between true puffballs and the usually poisonous earthballs.  The main difference between earthballs and puffballs is that, unlike the puffballs, earthballs do not release their spores through a regular pore.  Instead, the peridium (outer layer) cracks and tears irregularly.  Like all gasteromycetes (fungi whose spores mature internally), earthballs have lost the ability to forcibly discharge their spores.  The spores mature in the center of the earthball, enclosed by...

#040: Mushroom Morphology: Stinkhorns 2

Fungus Fact

#040: Mushroom Morphology: Stinkhorns

As the name suggests, this group is made up of the most pungent fungi. The defining characteristic of this group is that they all produce a dark, smelly slime that carries their spores.  This slime smells like rotting flesh for the express purpose of attracting flies and beetles.  The insects walk around in the spore slime and then fly away, carrying some of the mushroom’s spores on their legs.  After visiting a stinkhorn, the insects either land on real rotting material or on another stinkhorn.  In the first case, the rotting material serves as a substrate on which the spores can grow.  When the insect lands on another stinkhorn, this allows for cross-fertilization (much like insect pollination of flowers).  The other factor that all stinkhorns have in common is that they have a button stage.  All stinkhorns form a small, white, oval-shaped structure, or “egg” that contains the basic form...

#033: Mushroom Morphology: Morels 8

Fungus Fact

#033: Mushroom Morphology: Morels

It’s finally spring in North America! This has been a very long winter, but now the trees are starting to bloom.  To any mushroom enthusiast, this can only mean one thing: it’s the start of morel season!!  Keep your eyes peeled for these elusive mushrooms (especially under Tulip Poplars if you’re on the East Coast)!  What a morel looks like is a little hard to describe without a picture, so look at the one in the link below.  The head of the mushroom is the fertile surface and is defined by an exterior of irregular ridges and pits and a hollow interior.  This is often likened to a pinecone, though one with more color and less regularity.  The head is held above the ground by a stocky, hollow stipe.  The cumulative effect looks somewhat like a pinecone trophy.  There are four main species (or perhaps morphological groups) of morels in...

#026: Pseudogymnoascus destructans 5

Fungus Fact

#026: Pseudogymnoascus destructans

The fungus Pseudogymnoascus destructans is the causal agent of White-Nose Syndrome (WNS) of bats. WNS is most destructive to bats during the winter.  Its primary effect on bats is to change their behavior during winter.  Bats with WNS are observed to wake up frequently, fly around during the day, and cluster near the entrances to their hibernacula during the time that they should be hibernating.  This extra activity kills bats in two ways.  For one, they could either freeze to death while flying around outside.  Alternatively, the extra activity could deplete their fat reserves and the bats could starve to death.

#022: Nematode-Trapping Fungi 1

Fungus Fact

#022: Nematode-Trapping Fungi

Fungi have developed a variety of ways to trap and kill nematodes. These include: adhesive branches, adhesive knobs, adhesive networks, non-constricting rings, and constricting rings.  None of these fungi use nematodes as a primary food source.  However, fungi sometimes need extra nutrients, especially nitrogen.  Forming traps is very energy-intensive, so they are only formed when nutrients are scarce and nematodes are present.  Fungi detect nematodes by “eavesdropping” on ascarosides, the chemicals that nematodes use to communicate with each other.  If you want to see these fungi in action and/or get a better understanding of nematophagous fungi, watch the YouTube video (in two parts) linked below*.  For your convenience, I have noted the time at which each type of trap is discussed in the video.