Growing Sunflowers From Seed : When to Plant & How to Care for Them D&H Seed Harvest Co Plant Proteome in Response to Abiotic Stresses IntechOpen The Welsh Bunching Onion. A perennial onion that does not form an bulb in the roots however it keeps multiplying from the roots and within a years time could have up to Amorphophallus Titanum, the largest flower in the world. It blooms once every 40 years only for 4 days! Also called the Corpse Flower because of the smell