In Irish folklore Hungry grass or féar gorta is a patch of grass which causes great hunger and faintness if you step on it. If you don’t eat almost immediately you can die!
It grows where a famine victim died and is often in mountain areas. Older people always advised carrying an oatcake in your pocket if heading to the hills in case you stepped on some.
The schools collection mentions some Tipperary spots where hungry grass was reputed to grow.