“Texas tacks” are thorns that can destroy bicycle tires. They’re also called “bull heads” or “goat heads.”
   
 
http://nanaellen.com/psalm/gift.htm
Also, the pond was surrounded with an exceptionally nasty variety of burrs we Westerners affectionately call bull heads or Texas tacks.
   
 
http://web.tampabay.rr.com/vilmar/coast_to_coast_stories_oregon.htm
They were almost all victims of Texas tacks (or goat heads as other people call them.)
   
   
http://radek.com/usa91/
Beware of Texas Tacks or Texas Goatheads! Never ride through grass in this area! I only walked my bike for 5 meters through high grass and got two punctures in the front wheel.
       
 
http://list.massbike.org/archive/199907/0099.html
I used them on a cross country tour in ‘92 after being plagued by flats (‘Texas Tacks’ are what they call prickly vines that encroach on the shoulder of the roads). 
 
 
http://transam-bernard.blogspot.com
“Watch out for “Texas Tacks”, a parasistic thorn that is the scourge of bicycle tires”
 
   
http://scholar.lib.vt.edu/VA-news/VA-Pilot/issues/1995/vp950624/06230033.htm
By the time they reached Dodge City, Kan., they had worn out their tires and had to buy new ones. ``We got a lot of punctures in Kansas from long thorns called Texas Tacks’’ Kathy remembered.
 
     
Google Groups: net.bicycle
From:  hamachi
Date:  Mon, Jul 29 1985 12:57 pm
 
Specialized Expedition tires have been much better to me.  I put over 3000 loaded touring miles on one set with only 2 flats (I foolishly rode through a patch of “Texas tacks”), and there is still plenty of tread left.
 
 
13 August 1977, Daily Messenger (Canandaiga, NY), “Bicyclists Arrive At Mississippi River,” pg. 6:
“One story was about ‘Texas Tacks’ which exist on the roads o Western Kansas and Eastern Colorado. They’re little thorns which can become imbedded in the tired.”