狗牙根（学名：Cynodon dactylon），亦称绊根草（植物名实图考）、铁线草、爬根草、咸沙草，多年生草本植物。

狗牙根秆常匍匐地面上，节着土易生根，初夏抽花穗时，秆始上伸，顶生3-6枚穗状花序排成指状，夏秋开花。

Cynodon dactylon, also known as Vilfa stellata dūrvā grass, Dhoob, Bermuda grass, dubo, dog's tooth grass, Bahama grass, devil's grass, couch grass, Indian doab, arugampul, grama, wiregrass and scutch grass, is a grass that originated in the Middle East. Although it is not native to Bermuda, it is an abundant invasive species there. It is presumed to have arrived in North America from Bermuda, resulting in its common name. In Bermuda it has been known as crab grass.