 The usual flowering period of individual umbels is 7 to 10 days, so a plant can be in the process of flowering for 30–50 days.The distinctive umbels and floral nectaries attract pollinating insects.After fertilization and as seeds develop, the outer umbellets of an umbel bend inward causing the umbel shape to change from slightly convex or fairly flat to concave, and when cupped it resembles a bird's nest.