Possible Clues:

• Local fool blossoms before the summer holidays
• Flower that symbolizes paradise on earth
• Flowering bulb (from Amsterdam?)
• A bloomer injecting lithium into sheep
• I left upset ram without something it would eat?
• Flowering perennial
• It blooms in 11 down
• Black flower in a Dumas title
• Subject of an annual festival in Holland, Mich
• Single showy bell-shaped spring flower