Followers of this blog will recall that one of its recent posts discussed reproduction. I have chosen to pursue the phenomenon further by describing the life cycle of the Bear Lentinus, a Bascidiomyete fungus, shown below.

When human reproduction is concerned I believe that we tend think in terms of bodies making more bodies. Male and female contribute sperm and egg which fuse to form a zygote. Development then is the process whereby the zygote forms an embryo which undergoes a series of structural changes collectively called gestation. It is gestation which culminates in parturition. So two bodies produce a third. Now, some terminology. We say that gametes, sperm and egg, are haploid because they contain a single set of chromosomes (in humans this number is 23). As a result of fertilization, the cells which make up our bodies are diploid because they are derived from that very first cell which is the result of the union of egg and sperm. Bodies are diploid because each component cell carries two sets of chromosomes; one ultimately from each parent. Diploid bodies produce haploid gametes which participate in reproduction to produce diploid bodies once again. And, of course, the diploid body is what we think of when we think of people, or jellyfish, or cats, or starfish, or elephants, or oak trees. The diploid stage is what we know while the haploid stages, the sperm and egg, are hidden from view, they are cryptic. But what do you think of when you think of a fungus? My guess is that something shaped like a mushroom comes to mind. An edible, morsel you see wrapped in plastic at the grocery. Or perhaps you think of toadstools, puffballs, bracket fungi, or smuts. And, of course, these would all be correct. But these are all highly visible structures called fruiting bodies which are haploid and only one of many stages of a typical fungus life cycle.

For most of its life a basidiomycete fungus assumes a cryptic form called the hypha which is haploid (or possibly diploid, see below), mostly subterranean, and filamentous. A number of hyphae collectively form a mycelium. [This stage of the life cycle can be extensive indeed. The most humongous fungus is known to be one of the largest organisms on Earth; its hyphae are thought to occupy an area equivalent to 1000 football fields and the individual may be nearly 8,000 years old.] Among hyphae there are no males and females but instead monokaryotic hyphae comprise different mating types (+ and – if you like). These fuse in a process called plasmogamy which results in dikaryotic hyphae (containing nuclei of the two mating types but which have not yet fused). Dikaryotic hyphae coalesce as a mycelium which forms the familiar fruiting body which we know as a mushroom. Under appropriate conditions the nuclei within specific tissues of the fruiting body fuse in a process called karyogamy to produce diploid tissue for the first time. Meiosis, the very same process which produces eggs and sperm in humans, follows to form basidiospores which are liberated and then germinate to form monokaryotic hyphae once more, thereby completing the life cycle. As in all sexual life cycles variation among monokaryotic hyphae results because of the union of mating strains and the exchange of genetic information … the traditional (Darwinian) hedge against environmental change.

Boy, this seems unnecessarily complicated. Why go to such trouble? Perhaps some of the difficulty we may have in coming to terms with this life cycle stems from  a comparison with our own pattern of reproduction. Animal bodies are large, visible, diploid and long lived while animal gametes are small, cryptic, haploid and short lived. In contrast, fungal hyphae are small, cryptic, haploid and long lived … while fruiting bodies (mushrooms) are large, visible, haploid (and then very briefly diploid), and short lived. Perhaps, but what’s my point? My point is if you distill the essence of life … what it is to be living, alive … it is reproduction; and what’s more, there is no one best way of doing it. Reproduction involves passing chromosomes, genes, DNA, into the bodies of those that follow. And they pass DNA into more bodies and so on. And it isn’t necessarily the chromosomes themselves that pass into future generations … but rather the messages encoded by them. But maybe this final thought is a topic for another day?


11 thoughts on “‘Shroom

  1. What a sensuous shot of an amazing mushroom. I love all the science you pack into your posts, this one is no exception. I’m a huge fan of mushrooms and their wonders, they seem so mysterious with most of their bodies hidden away under the earth….and some of them taste delicious 🙂

  2. You should have presented this image as a puzzle – I guess I would have never guessed this is a fungus but rather expected it to be identified as something related to animals, probably a close-up of a paw 🙂 I am living in an old house whose cellar was not at all compliant with contemporary building codes for a long time. Thus when I read ‘fungus’ I thought of that fungus that grows in white and fluffy patches. When it grows on the floor undisturbed in interesting regular patterns or covers dead spiders with a white layer I even see some beauty in this (the cellar is drained and dry now ‘unfortunately’). I was most impressed by a particular black and very fluffy variety of mold fungus, visiting one of the largest wine cellars in Austria – an impressive underground maze. It had once been setup by monks who knew how to build such infrastructure in a way allowing for some feeble, but constant ventilation and for a nearly constant temperature throughout the whole year (and in such a low-tech way …). I have been told the black fungus is an indication of the perfect microclimate for fermenting wine. Fungus rules! 🙂

    1. My mycologist friend here in the department would agree with you last sentiment. Certainly fungi rule … and they are very much unappreciated. Thanks for your mycological observations today. Much appreciated. D

  3. Dave, your ‘eye’ gets better and better. The luminosity of that soft edged fleshiness, fading off focus towards the back … downright sensual. I’ve had to make a special folder for your images as they move off my desktop. This lovely ‘shroom is the new desktop today. Some I keep for ages, some don’t last that long before another great image comes along. Your images so often remind me of the possibility of moments of perfect beauty, if we take the time to notice and train the brain to observe. This one is especially nice. Thanks.

    1. You are oh so good for my self-image. You know sometimes our blood pressure rises for the wrong reason (mostly frustration and irritation). As I read your comment however my blood pressure rose for just the right reason … wonderment and elation that someone had really understood the intention of the image! [And the professional qualifications behind your written words make them that much more valuable.] Horray! [Let it be our dirty little secret that you are on the payroll to keep those choice comments coming my way.] I am now fortified with positive energies to take on the remainder of my day. Charge! D

      1. I certainly don’t want to be bad for your blood pressure! Can’t wait to see you all at Thanksgiving! Give Joanna a hug from me 🙂

  4. When I read the title I was transported back to a time, around 32 years ago. I’d spent the whole summer putting money aside to buy a new tape deck for my sound system. I wanted the new Panasonic model that had the DBX noise reduction system instead of getting one that ‘merely’ had Dolby. The only place I could get it at reasonable cost was by mail order from a firm out of Baltimore called International HiFi. All told it was around $700, a princely sum for 1981! It arrived at YYT and was held there fro pickup by Air Canada cargo. I hit up my friend Alf for a ride there and picked up my precious package. On the way back I got Alf to stop by a gas station so I could put a few $$$ in his tank for his trouble. The attendant was a seedy young fella who looked and acted just a bit off, giggling away to himself as he put the fuel in. He came to the window and I handed him the money. He put it in his wallet, looked as, while grinning away and asked, “Ever try the ‘shrooms, boys?” Alf and I laughed the whole way home. No, we had not tried them but were quite used to the stoners out there on the University lawns, picking away at the magic mushrooms in the fall of the year. Hmmm at a time just like this one! Pretty sure they didn’t much care about how they got there, either.

    On a more serious note your piece reminds me of the fact that I’ve always regretted not having studied Biology beyond high school. I used to enjoy it and did well–if I recall it was always my strongest subject. Unfortunately I decided to major in physics and become a HS teacher. That decision left me with very little choice in what I did owing to the fact that Physics majors have to also do a far bit of math and chem. Can’t do it all I suppose. On that note I will say that as far as I can see, the further we advance, the more mysterious the whole thing gets, regardless of whether it’s physical, earth, environmental or life science.

    A little postscript: the tape deck was great. Dolby reduces tape hiss using filtering an by selectively boosting and attenuating certain frequencies. The main thing to get rid of is tape hiss–random magnetism along the tape. It’s confined mainly to a particular frequency band. Dolby boosts ‘wanted’ sounds within that band stronger to increase the signal to noise ratio. On playback it attenuates that same range to make the previously boosted real sounds normal again while, at the same time, reducing hiss. DBX uses a completely different method. It re-maps the frequency bands to avoid the tape hiss area, more or less. By avoiding that band it does an even better job. It never really took off, unfortunately as it remained expensive. If you recorded in DBX you could only play it back in DBX. This meant you could not play back your stuff in the car unless you wanted to spring for an expensive player there too. Sort of like VHS vs. Beta. In the end the ‘better’ but more expensive Beta lost out to cost. No odds, within a few years digital took over everything anyway. The tape deck did work flawlessly for 30 years, though.

    OK, one final, final thought. As for your remark on the humongous fungus, you triggered this thought as I was reading the rest of the post: it is so very amazing how much living material is essentially invisible to us, from the small plant life that lives in the sea right to the massive quantity of bacteria that live within (and help) us all, isn’t it! OK, that’s it. Off to bring the boys to Uni, then bring a load of what was the roof of my shed off to the dump, a trip to get new shingles & felt and then, finally to shingle the new roof. II’m replacing the old felt over OSB, which has had it, with shingles over plywood. Should have done that in the first place. Snow tomorrow. Sorry, had to close with the “S” word.

    1. Thanks for the stories … we are of a generation you know so your excitement about the tape deck reminds me of many trips to a store near by parent’s home called Twitter. I went there routinely, as a 14-18 year old to drool over the desks, amplifiers, and speakers. Especially the latter. Can still remember my 8-track and the twin-deck cassette player … ah, those were the days. I can also remember installing a nice pair of Jensen speakers in my 1979 (White) Camaro! I wonder what we would have thought then about today’s totally crazy car sound systems? Thanks also for the information on Dolby versus DBX … I always appreciate learning stuff that I do not know. As for your observations concerning our ‘invisible’ world … agreed . .. cool beans. And, finally, you have your work cut out for you today … don’t fall off any ladders. I will revel in my safe, quiet, and foot-on-the-ground lecture hall today. D

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