Wednesday, August 18, 2021

SearchResearch Challenge (8/18/21): What are those things on the ground that hurt my feet?

That tree... 

The canopy of the mighty oak the back yard is, I was told by the arborist, a black oak.  

It’s certainly an oak—it rains acorns in the fall, loses all of its oak-shaped leaves, and is tall and massive—it’s a lovely paradigmatic example of an oak.  The arborist who tended to it when it was still a sapling told me it was Quercus velutina, a black oak.  

This morning was cool and overcast, perfect for walking around in the backyard under that oak tree with the picture-perfect spreading limbs.  Ah.. the verdant life!  

Except that when walking around in bare feet, there are lots of acorns and zillions of small, very hard, nubby things that feel like Lego blocks underfoot.  It's a beautiful tree, but it also sheds a ton of things that are painful to step on without shoes.  

To say that I’m curious about many things is probably an understatement.  So of course through my pain I immediately wondered, “What are those things?”   

This is what the yard looks like up close:  


You can see a few leaves, an acorn, the cap of an acorn, and lots of those small brown knurled balls, each about 6mm (about 1/4 inch).  I don't know what they are, so I'll call them nubbins until I figure out what they actually are. They’re everywhere.  But what are they?  

I plucked a small stem with a few leaves, an acorn, and a couple of the mysterious nubbins.  Here you see a typical branch end:  

And a bit of a closeup so you can see the objects of interest... 

The nubbins attach to the stem just above the acorn.  Here you can see two of them, but often there will be 1, 2, 3 or 4 nubs.  (Never more than that.)  

And here’s a photo with everything taken apart: 

I spent a little time SearchResearching this one--and finally figured it out.  I won’t tell you all the ins-and-outs of my search, until next week.  

Afterwards, I also realized that the pain in the soles of my feet would make for a great SRS Challenge for the week.  While doing this I learned a good deal about how to search.  Can you answer these Challenges? And what can you learn in the process?  

1. What are those nubbin things?  Is there a name for them?  

2. What do they do for the tree?  Why would a single tree generate so many of them?  (I estimated, using Fermi estimation) that this tree produces around 100,000 of these per year.  So over the past 10 years, that's a cool 1 million nubbins (or whatever they are).  What's the point from the tree's perspective? 

Can you figure it out?  If so, let us know what you did to get to the answer.  

Search on!  (Botanically!)  



  1. Another great and interesting Challenge!

    I was searching using Search by Image with the three photos. I didn't find anything good.

    Then tried with words. I used [Black Oak diagram] , [Black Oak Acorn diagram] and similar.

    Then tried with Black Oak identification. No answer.

    Finally, downloaded the images and searched with Google Lens (before that, I even tried Yandex]

    Photos 2 and 3 gave me no good results. However, with photo 1, I think I found this answer.

    They are : Galls on Oak Trees! They are produced by wasps that leave their eggs in the trees. That made me remember figs that are also related to wasps.

    I am currently reading more about the galls. Some say they eventually kill the trees. Other (majority) mentions it's only a problem if they are plenty of them.

    1. With [Oak galls formation] good results on All tab and also on videos.

    2. Another video. This one from BBC (12 years ago) Also read , in the description of another video) that ink can be produced with the galls.

    3. Searched for the difference between Fig wasps and Oak wasps. I found this, from Britannica, and it's ver interesting

      More about figs and wasps. In Spanish

  2. [oak tree small brown knurled balls, each about 6mm (about 1/4 inch)] finds articles like this:
    How to Get Rid of Oak Galls

    treating your tree will keep you busy for quite awhile...j who thinks he can trust this source, having read your good advice last week.

  3. Here's a giant tip for everyone: They're not galls! (I totally understand why you might think that.) Next week I'll talk about why they're not. Stay tuned!

    1. After reading you, thought that the other option is undeveloped acorns. Searched [undeveloped oak acorns] and in images found similar (gals also looked similar, so maybe it is not.) And found these could be aborted acorns due to stress and other situations that protects the trees.

      However, searched [aborted acorns oak tree] and haven't found articles]

    2. Searched for aborted acorns on YouTube. Found this. Masting Years in Oaks trees and cicadas too.

    3. With [aborted oaks acorns]

      Oak Trees Aborting Acorns

  4. They looked like acorn caps to me, so I searched for "acorn caps without acorns on oak tree" and found this reference to aborted acorns:
    Here's another reference to immature acorns: AND
    I can't vouch for these sites,but perhaps your tree is dropping immature acorns.

  5. Replies
    1. Speaking of painting – What is your Fermi estimate for when we will have the paint needed for Gabriel’s Horn?

    2. brush or roller… where is Bob Ross when magic white is needed…? Enrico sold his painting business some time ago - think Hyundai bought it…
      inner or outer surface - a möbius surface of sorts
      one sided
      liquid white
      Toricelli’s trumpet
      also curious
      Torricelli's law

    3. So - are you going to fill up the Horn or just paint the surface? You might as well apply two coats, it uses the same amount of paint.

    4. In either case, while the Horn is infinite, all paint has an actual particle size. Titanium dioxide (a common white paint pigment), is around 0.02 microns in size. All you have to do is to integrate the volume function from zero . That will limit the "paint" required. (Unless you're talking about mathematical paint..)

    5. if only Gabriel had played the bongos… is math language or is language math?… or simply a virus…

    6. True - integrating the volume function to infinity give a finite value (pi). But integrating the surface area gives infinity so it would take an infinite number of paint particles to cover the surface. My Calculus students didn't believe it either.

      I like the idea of mathematical paint. It could be continuous instead of discrete.

  6. Assuming the nubbins are what we think they are (so far):

    I wasn’t sure if the second challenge was asking the tree’s perspective about producing the inchoate acorns or shedding them, but I searched

    [aborting acorns benefits oak trees]

    and from this trustworthy site


    “Oak trees often abort acorns during periods of stress, thereby conserving resources such as water and nutrients. This benefits the tree by redirecting resources away from seed production and into more critical life-sustaining processes.”