Monthly Archives: September 2026

Acorn or Gall? Update!

An Albuquerque Park Mystery #26 —Mystery Solved!

September 8, 2026

It’s not about what it is, it’s about what it can become. — Dr. Seuss, The Lorax

The creation of a thousand forests is in one acorn. — Ralph Waldo Emerson

Super thanks to Dana P., a regular reader of my blog and a very savvy observer of my recent post, Acorn or Gall? Dana instantly recognized the mystery oak as Bur Oak (Quercus macrocarpa) from my sketches of the leaves and acorn! “Way to go Dana!!! I’m so grateful you commented and then generously allowed me to share your photos.”

So, those shaggy pale green balls growing from the ends of many leafy branches are acorns after-all. The acorn I collected was apparently immature; that scary-looking tentacled orb was the cap (cupule) still tightly enclosing the growing fruit (the nut). 

Dana has a lot of experience growing Bur Oak, some of which were germinated from collected nuts (see Dana’s photo below). Now we all can see how a mature acorn appears when nuts are ready for harvesting. (I still think they are the weirdest acorns ever, don’t you?)

The next photo proudly displays three ‘baby burs’ that sprouted from Dana’s successful germination efforts. The nuts, harvested in the fall from a very old Bur growing in Nashville, Tennessee, were planted in the pot and allowed to overwinter outside, on a screened-in porch to prevent squirrel-theft. They emerged as little trees the following spring. These healthy sprouts in the photo have been happily living in east Texas for the past four years and have grown to four feet tall! 

And now for a bit of acorn anatomy (you knew I couldn’t resist!).

The term “acorn” refers to the entire unit; the cap (cupule) and the oak fruit (nut). 

Exterior Parts

Cupule – the botanical name for the acorn’s ‘hat.’ It’s the cup-shaped or bowl-like cap made of hardened, modified leaves called bracts. The outside features scales that can be flat and smooth, bumpy and warty, or loose and fringed depending on the oak species. The cupule protects the nut and helps attach the acorn to the tree branch while it grows.

Pericarp – the hard, tough outer shell that encases the inner kernel of the nut.

Stem – the tiny twig attachment point at the base of the cupule.

Interior Parts

Seed Coat (testa) – the thin, papery layer just inside the outer shell that directly covers the nut meat.

Cotyledons – two large, fatty seed leaves that store starches, proteins, and fats to feed the growing plant (and wildlife).

Embryo – the tiny baby oak tree nestled between the two cotyledons at the pointed end of the nut, consisting of the plumule (future shoot) and radicle (future root).

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Always be Curious

As always, thanks for stopping by!

Acorn or Gall? 

An Albuquerque Park Mystery #26

September 6, 2026

The date: August 24, 2026 

The time: 8:30 am. 

The forecast: Severe clear; calm winds; 82oF & climbing

The place: The Promenade in Albuquerque  

The destination: el Oso Grande Park (“The Big Bear”)

After dropping Roy off for his annual eye exam, Luna and I decided to ‘sniff’ around the neighborhood on our way to nearby el Oso Grande Park. With the chance of rain being “zip,” I was confident walking east along a half-mile stretch of the large cement ditch used to drain storm water from Embudito Canyon. Other than creatively colorful graffiti, the ditch itself had nothing interesting to offer. The hot paved walkway, mostly lined by weedy species, provided perfect habitat for scattered bushy sacred datura plants in full bloom. The many city dwellers living ditch-side allowed landscaping plants to cascade over cinderblock privacy walls — the patches of shade – welcome; sprays of pale pink to magenta desert willow flowers – pretty and fragrant.

A sweaty 20 minutes later and the shady expanse of the Park was a welcome sight. Not one to waste time, Luna anxiously led me to tree trunk #1, circling and sniffing excitedly three times ‘round. Not being able to smell the wonderfully curious aromas capturing her full attention, I spent my time looking up into the leafy canopy of this full grown deciduous tree planted years ago in memory of a once local resident.  

We moved on to tree #2, a robust conifer towering over the well-manicured green lawn, supported by another aromatic trunk recently ‘watered’ by a happy dog walking their human. Before we could check out tree #3, Luna claimed #2 by leaving her ‘calling card.’ 

And on and on we wandered and circled, until ….

…. I realized, based on our exam speed/tree (largely driven by Luna’s satisfaction meter), our Park tour of over 100 trees would take a month of Sundays! So we ramped up our pace, making  decent progress to (hopefully) ensure our timely return to fetch Roy …. then tree #26 happened! 

Oh! What was #26? Now it was my turn to encircle a tree, and I couldn’t stop.  In addition to the puzzled look on Luna’s sweet face, several other things were certain: 1– this very large tree was a 2– deciduous 3– dicotyledonous member of the 4– oak genus Quercus. The deeply-lobed leaves were a giveaway, even though most of each leaf’s margins were dried and crinkly. But it wasn’t the leaves catching all of my attention — it was the 1-inch diameter shaggy pale green balls growing from the ends of many leafy branches. This certainly didn’t look like any acorn I’d ever seen before …. besides, right beside this scary-looking tentacled orb was a single mini-acorn that tried but never fully developed — only the dried, withered acorn cup had partially formed before rotting. 

So what was it that sucked the life right out of that tiny failed acorn, and grew into something alien?  If this was some kind of acorn that grows on a non-native oak tree I’ve never seen before, then I had to learn more! If this was a gall, an unusually grotesque, weird and exaggerated growth stimulated by a developing wasp grub living deep inside, then I really had to learn a lot more! 

And then I collected and promptly zip-locked a specimen.

This became (and still is) An Albuquerque Park Mystery hanging like lime green ornaments all over, and also within reach from, tree #26!

P.S.

  • iNaturalist identified the tree as Gambel’s oak 
  • Never have I ever seen a Gambel’s oak acorn look like that!
  • Still waiting for an oak expert to identify the tree leaves and/or acorn/gall-thing

P.S. P.S.

  • So many questions remain
  • Upon arriving home, no wildlife observed inside zip-locked bag
  • I dissected the growth, inside and out — found what looked like an acorn nut 
  • No sign of a grub; no exit holes in the outer or inner shells

P.S. P.S. P.S.

  • Luna & I practically ran back to the eye doc’s office, arriving minutes before Roy’s exam concluded

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If you’ve seen anything growing on an oak that remotely resembles these mystery green goblins, please let me know what it may be, and what species of oak they come from! 

As always, thanks for stopping by!

P.S. P.S. P.S. P.S.

  • When “An Albuquerque Park Mystery #26” is solved, you’ll be the first to know!