“Where do baby citrus fruits go to learn?”/“A lemon tree school.”

“Elementary” sounds like “a lemon tree.” “Err…where do lemons go to get educated? A lemon tree school” was posted on Twitter on July 25, 2012. The riddle was posted on Reddit—Jokes on October 8, 2017:
 
Q: Where do baby citrus fruits go to learn?
A: A lemon tree school.
 
There are several real schools named “Lemon Tree School.” “The Lemon Tree School” is a company located at 510 East 89th Street in Manhattan. “Lemon Tree Preschool” is located on Staten Island.
     
 
Google Groups: atl.fan.holmes
“Elementary, my dear Watson” 
Mark Israel
4/20/94
In article <2p3dh0$c…@carina.unm.edu>, roger m squires

writes:
> And here’s another really tired oldey:  What is the
> origin of “Elementary, my dear Watson”?
     
I think it’s a corruption.  It may come from the time Holmes was swallowed by a whale, and remarked “Alimentary, my dear Watson.”  Or it may come from the time Watson asked his old friend what his favourite tree was, and Holmes replied “A lemon tree, my dear Watson.”
   
Holmes says “Elementary” in “The Crooked Man” and writes “My dear Watson” in “The Final Problem”, but the first recorded juxtaposition is in the 1929 film _The Return of Sherlock Holmes_, the first Sherlock Holmes sound film.
 
Twitter 
Nick Nash‏
@Bright_Sorcerer
Watson: “What’s your favorite tree, Holmes?” Holmes: “A lemon tree (elementary), my dear Watson.”
11:57 PM - 2 Jun 2009
 
Twitter
B-rad Drummaboi™ ツ‏
@GODSCHOSENSAINT
A Lemon Tree = Elementary
2:51 AM - 10 Mar 2011
     
Twitter
Chris‏
@ThisIsChris_x
A Lemon Tree - Elementary. It’s a Sherlock Holmes joke.
6:19 AM - 12 May 2012
 
Twitter
Phil Gibson‏
@philgibson01
Err…where do lemons go to get educated? A lemon tree school.
8:17 AM - 25 Jul 2012
 
Twitter
Deplorable Eric West‏
@EricJWest
Replying to @heilaredpath
.@heilaredpath @inixza @johanpberg Yes! That’s what my late Dad used to say! And, for anyone who didn’t get it “a lemon tree” = elementary.
11:27 AM - 1 Mar 2013
 
Twitter
Raj S‏
@XYZRaj
#treestv A-Lemon-Tree (Elementary)
9:43 AM - 3 Mar 2013
 
Twitter
Nicholas A Thompson‏
@nickthxmpsxn
“Its weird not having any kids in ‘a lemon tree’ (elementary) school this year.” -Nicks Mom 2016
8:09 AM - 22 Aug 2016
 
Reddit—Jokes
Where do baby citrus fruits go to learn?
submitted October 8, 2017 by Monkfi5h
A lemon tree school