three-cornered leek vs triquetrous leek

three-cornered leek and triquetrous leek both are nouns.

Word	Noun	Adjective	Verb	Adverb
three-cornered leek	Yes	No	No	No
triquetrous leek	Yes	No	No	No

As nouns, three-cornered leek and triquetrous leek are synonyms defined as:

three-cornered leek and triquetrous leek: European leek naturalized in Great Britain; leaves are triangular

Other synonyms of three-cornered leek include Allium triquetrum.

three-cornered leek (noun)	triquetrous leek (noun)
European leek naturalized in Great Britain; leaves are triangular	European leek naturalized in Great Britain; leaves are triangular