Weed growing inside toilet pipe

An individual posting to the forums on HouseRepairTalk.com reports recurring problems with a strange and motivated plant that takes root under their toilet and grows into the drain pipe. From the forum:
 Albums O52 Infectious Sense House Pottyweed1-23 Over the past few months, the toilet would drain slowly. We plunged, we snaked, we blew out the clean-out drain with a blow bag - everything. We called a plumber, who used an auger to go down the drain and pulled out some large clumps of gunk... and also told us to replace our wax ring - that it might be old. The toilet flushed for about 24 hours, but when it began to slow again, we went and got the wax ring replacement. Upon removing the toilet to replace the wax ring, there it was AGAIN! This time - more than twice as long!
"The Potty Weed - HELP!!" (Thanks, Tara McGinley!)