In north Texas, we are far enough from the ocean to have four distinct seasons, and we are far enough south that we generally have long, hot summers and short, mild winters, and usually enough pleasant weather in spring and fall that we can open up the house for days, even weeks at a time.
Unfortunately, we also have four allergy seasons. Late summer and fall is ragweed pollen season - more on that later. Winter is mountain cedar pollen season (more appropriately known as Ashe Juniper because it is not a cedar and is not restricted to mountains) - I am particularly allergic to this one. Spring is grass/tree pollen season, with a medley of pollen in the air. Summer is fungus spore season. We are right in the middle of that. The “pollen count” in Dallas has been running at least 7000 grains/cubic meter of air, and is nearly 9000 grains/cubic meter today (with a little ragweed mixed in for good measure). Even during other allergy seasons here, there is a chronic background level of fungus spores that is often greater that the levels of other pollen.
One of the worst offenders among the spore-producing fungi is the puffball. There are several species of puffball-producing fungi in North America, many of which are in the genus Calvatia. The puffballs we have in this part of north Texas are mostly Calvatia cyathiformis - this specific epithet refers to the cup-like morphology of the puffball.
An individual puffball may release trillions of very tiny spores during the few weeks that it is “active” above ground. Release of spores from puffballs is triggered by mechanical stimuli (wind, raindrops, people poking them with sticks, etc). The spores of C. cyathiformis seem to be particularly allergenic - I don’t know whether that is because of their spiky surface of some chemical characteristic. Once the puffball is spent, it deteriorates.
(scanning electron micrograph of C. cyathiformis spores; image from http://www.nemf.org/files/sam/Spores/sporeshow/fv19.htm)
Puffballs, mushrooms, and shelf (AKA bracket) fungi are the sex organs of various species of fungi within the fungal taxon Basidiomycetes.
(a "chicken mushroom")
(a "fairy ring" of mushrooms)
(a "bracket fungus")
The body of the fungus (the mycelium) is under the ground. The mycelium of large fungi may cover many square feet and weigh many kilograms. In fact, mycologists claim that the largest living organism (and potentially the oldest) is a fungus. This seems even stranger when you know how the body of a fungus is constructed. The mycelium comprises a large number of very small tubes called hyphae. Hyphae have an outer covering of chitin that is semipermeable, and they contain cytoplasm, organelles, and nuclei, like "normal" eukaryotic cells. The hyphae branch and anastomose, and form a dense mat, but they are still just very small tubes (2-10 microns, much finer than a human hair).
This is an alien way to structure the body of an organism, but it works for the fungi. Fungi make their living by being “absorptive heterotrophs,” which means they are not photosynthetic (autotrophic), but instead take up organic material from the environment by first secreting enzymes to digest the material, then absorbing it into the hyphae. Having a body composed of a huge number of fine tubes increases astronomically the surface area for secretion and absorption.
Fungal reproduction, at least within the Basidiomycetes, is a bizarre affair. The spores produced by puffballs and their ilk are “haploid,” having only one of two sets of chromosomes, and being produced by the cellular process of meiosis. The spores are akin to sperm and eggs produced by humans and most other vertebrates. The spores germinate to form hyphae, and the hyphae grow into what is called a primary mycelium. Each primary mycelium is either “female” or “male” (mycolgists don’t use these familiar terms, but the gist of it is the same).
If a female primary mycelium encounters a male primary mycelium, they coalesce to form a secondary mycelium. You would think, at this point, that the female haploid nuclei would join with the male haploid nuclei, like a sperm joining with an egg to form a diploid individual. But NO, the fungi don’t do it this way. They keep their haploid nuclei separate but living in the same body, sometimes for years, until it is time to make new spores. Then the secondary mycelium produces basidiocarps (the puffballs, mushrooms, and bracket fungi that are the genitalia of the fungus). Within these structures the nuclei come together to form diploid nuclei (the process is called karyogamy), then immediately undergo meiosis to form haploid spores. These are the spores that cause so much misery among allergic humans. Bizarre!
This cartoon will illustrate:
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