Corolla with a spur: in some species the corolla has an obvious outgrowth which serves as a collector of nectar, called spur:
Examples are the flowers of Delphinium
...those of the genus Aquilegia
...the flowers of several orchids..:
...those of violets...
...and those of several other species of herbaceous plants.
In some cases the 'spur' is very short and sac-like, e.g. in the genus Fumaria