The Conjugation Fungi

sexual reproduction in the bread mold fungus

"Conjugation fungi" is sort of a clumsy name for this group. The name reflects the fact that among these fungi, instead of the spores being produced on conspicuous spore-producing bodies such as mushrooms or cups, they are produced in very small structures that form when the fungal hyphae "come into conjunction," or meet one another. The above diagram shows what happens. Two hyphae "come into conjunction," bulges form on each of them (the progametangia), and this leads to the mature "zygospore." In fact, in technical texts this group is often referred to as the Zygomycetes or Zygomycota.

Something important to notice in the above diagram is that the dots, which represent cell nuclei, are not separated from one another by cell walls!  Therefore, the big things about conjugation fungi is that

  • they don't form conspicuous fruiting bodies
  • no cross walls separate cell nuclei

The diagram above shows how zygospores are produced through a sexual process. Conjugation fungi can also reproduce without sex being involved (asexually) to produce just plain spores.

Bread Mold Fungus

Bread mold fungus, Rhizopus nigricansThe picture at the right, believe it or not, shows one of the most common fungi in the world, the Bread Mold Fungus, Rhizopus nigricans. A few days before the picture was taken some water accidentally seeped into a package of cornmeal. When I finally opened the package, the cornmeal was spoiled and its surface was covered with the stuff appearing in the upper two-thirds of the picture. The lower third showsthe  grainy cornmeal. The size of the cornmeal granules shows how much the picture has been magnified. Now, the black specks in the upper two-thirds of the picture are tiny sporangia which are asexual structures producing spores. The grayish material surrounding the sporangia is a mass of tangled and branched hyphae and the stalks (sporangiophores) atop which the sporangia appear. Again, the diagram at the top of the page shows sexual reproduction, but here we're seeing asexual reproduction.

If you want to see just how common bread mold is, a good experiment for you to make, wherever you happen to be in the whole wide world, would be to take a piece of bread, slightly moisten it, touch the bread to a table top or anything around you, then put the bread aside for two or three days in a warmish place where the bread won't dry out -- maybe in a small sealed container or a plastic bag. I'll bet that mold grows on your bread, and probably it'll be bread mold fungus. When you think of the number of bread mold spores that must exist in the whole world for this experiment to work, it's mind-boggling.

Return to the FUNGUS MENU
Return to the PLANT MENU
Return to the HOME PAGE