The closed and imperfect flowers are, however, manifestly of high importance, as they yield with the utmost safety a large stock of seed, with the expenditure of wonderfully little pollen.

The two kinds of flowers often differ much, as just stated, in structure.

The petals in the imperfect flowers almost always consist of mere rudiments, and the pollen-grains are reduced in diameter.

In Ononis columnae five of the alternate stamens are rudimentary; and in some species of Viola three stamens are in this state, two retaining their proper function, but being of very small size.