I heard from a friend about a plant that I could use for birth control that is natural and safer than the little pills i get from my doctor. You know of it? Nancy K. Ah yes, the old laserwort myth. The seed of the silphium plant, used in ancient times as an herbal contraceptive, has been suggested as the source of the heart symbol. Sure, this theory checks out in some of the oldest images of this seed — those found on ancient Cyrenaic (now Libya) coins. However, if you look up a plain old “silphium seed” the results are less convincing. Also, the “contraceptive” part?