Lily-of-the-Valley (Convallaria majalis)
Why we grow it: Low to the ground with spires of tiny, white bell-shaped flowers, lily-of-the-valley packs a potent, sweet-smelling scent despite its small size. It's also an excellent groundcover in shady settings.
Deadly parts: The entire plant, particularly the leaves.
Toxic toll: Sure, they make for an attractive flower arrangement, but even the water you place cut lily-of-the-valley flowers in contains deadly traces of convallatoxin, which intensifies the heart's contractions. Just a bite causes headaches, hot flashes, hallucinations, and irritability, not to mention red blotches on cold, clammy skin. The heart will also slow down, potentially leading to coma and death.