Field of Science

The fungus amongus - mycotrophy

TPP has a curious relationship Richard, a former undergrad student who has assisted with my tropical field research.  You see, Richard is the older of us by a decade or so because he got his BS in biology as a retirement project.  He also has an insatiable curiosity that drives him to scan science journals and web sites looking for articles of interest, which he then passes along to this correspondent. 
Here's a news item about an orchid that lacks chlorophyll and never opens its flowers. A number of plants produce cleistogamous flowers that never open and therefore are obligate selfers.  Not sure how an orchid does this because the pollen and stigma are quite separate & the pollen is in a waxy mass.  The pollen tubes must actually grow through floral tissue.  Plants lacking chlorophyll is not unusual, but they are generally parasites on other plants (e.g. Indian pipes).  This particular orchid is mycotrophic (literally fungus feeding) meaning that it derives its nutrition from an association with a fungal mycellium, the filamentous body of a fungus.  Fungal organisms like this can be huge and very old, but we seldom notice them because they live in the soil only sending up their reproductive structures (mushrooms).  Orchid seeds are tiny, so-called dust seed, and their seedlings are equally tiny and most if not all count on an interaction with fungi in this early stage to survive. Apparently some never out grow this interaction and have evolved a dependency on its fungus.  Here in N. America, the non-green, mycotrophic, coral root orchids (Corallorhiza) are fairly common, but they do flower (usually woodland in summer or early fall) so we see them now and again.  So the combination described in Richard's article is pretty unique. It also explains why such plants are so uncommon and so hard to discover. Sorry the images are under copyright so you'll have to go look to see them, but as you may guess, non-opening, underground flowers are not very showy. 

1 comment:

Larissa said...

The timing of this post is interesting. Did Mrs. Phactor tell you about our introduction to "Mother Trees" the other day?