• Gardeners looking for an exotic flower accent will find that tropical flowers often have the most unique and eye-catching blooms, although some native flowers have equally unusual shapes. Gardeners who prefer white flowers have a handful of exotic specimens to choose from.
  
  

Alligator Bonnet

• Also known as fragrant water lily, alligator bonnet (Nymphaea odorata) is a flowering perennial that offers showy, crisp white flowers that may be up to 9 inches in diameter. The flowers are sweetly fragrant, and typically appear throughout the summer. Flowers sit atop or several inches above broad, green lily pads. Alligator bonnet makes an exotic addition to a pond or shallow container, growing in as little as 3 inches of water. Plant alligator bonnet in water as deep as 6 feet in USDA Plant Hardiness Zones 3 to 11. The water lily will produce its best blooms if grown in full sunlight.
  
  

Mountain Bluet

• Growing 1 to 3 feet tall, mountain bluet (Centaurea montana 'Amethyst in Snow') is a flowering perennial that can be used as an unusual addition to a flower bed or border. Flowering in late spring and summer, the plant offers white flowers accented by a glowing purple center. Plant mountain bluet in a well-draining alkaline soil in partial or full sunlight in zones 3 to 9. The plant prefers somewhat-dry soil, so supplemental watering is usually unnecessary. Check occasionally for diseases such as rust, mildew and thread blight, which all commonly afflict the plant.
  
  

White Butterfly Ginger Lily

• A native of India, white butterfly ginger lily (Hedychium coronarium) is a flowering perennial that's gained popularity as an ornamental in subtropical and tropical regions. Growing 3 to 7 feet tall, the plant produces large green leaves accented by fragrant white flowers that have a distinct, butterfly-like shape. The fragrant flowers appear in midsummer and continue blooming until the end of the season. White butterfly ginger lily is suitable for zones 7b to 11, and the plant will look its best if grown in partial or full sunlight in a well-draining, fertile soil that's kept moist to the touch.