We are offering Nigella seeds have little odour, but when ground or chewed they develop a vaguely oregano-like scent. The taste is aromatic and slightly bitter.nigella have long been used as a medicinal treatment called a cure for "everything except death�. they are often mistakenly called onion seeds because they have a slight onion-like smell. Nigella sativa is an annual flowering plant. It grows to 20�30 cm (7.9�12 in) tall, with finely divided, linear (but not thread-like) leaves.