skirret Sium sisarum, also called water parsnip, an umbelliferous and perennial plant whose root used to be eaten until the spreading popularity of the potato ousted it. The root is branched, like that of scolymus (see under salsify), but unlike the other root vegetables in the family (carrot, parsnip, salsify, etc.). Each branch is about as thick as an early, forced carrot, grey outside and white inside, with a flavour resembling that of celeriac (see celery), but sweeter. Old roots have an inedible, woody core.
