Source : Webster's Revised Unabridged Dictionary (1913)

Alliaceous \Al`li*a"ceous\, a.
   Of or pertaining to the genus {Allium}, or garlic, onions,
   leeks, etc.; having the smell or taste of garlic or onions.

Source : WordNet®

alliaceous
     adj 1: of or pertaining to the botanical genus Allium; "onions,
            leeks, garlic, chives are alliceaous plants"
     2: smelling of onions or garlic