08:15 AM CDT on Sunday, July 1, 2007
By DEREK KRAVITZ / The Dallas Morning News
dkravitz@dallasnews.com

CADDO LAKE, Texas - Every day, a handful of locals climb into small paddleboats on this scenic lake and scour its shallow, swampy sloughs and bayous for signs of a monster.

The tropical import from Brazil can double in size in less than a week  clogging waterways, choking out natural vegetation and killing off bass.

Retirees and fishermen fear the weed could soon turn Texas' only natural lake into a massive green parking lot.

"You can't stop it," said Billy Carter, a 57-year-old Caddo Lake bass fisherman and tour guide. "How do you stop something that has no beating heart and that can reproduce in a few days?"