a) Flowers pollinated by the wind (Anemophilae, wind-flowers).
b) Flowers pollinated by water (Hydrophilae, water-lovers).
c) Flowers pollinated by animals (Zoidiophilae, animal-lovers).
Flowers pollinated by animals may again be subdivided into:
Snail-pollinated flowers (Malacophilae).
Bat-pollinated flowers (Chiropterephilae).
Bird-pollinated flowers (Ornithophilae).
Insect-pollinated flowers (Entomophilae).
Flowers pollinated by insects may again be divided into:
Flowers visited by miscellaneous insects, moth-flowers, fly-flowers, butterfly-flowers, bee-flowers, bumblebee-flowers, wasp-flowers.
Flowers may be divided into pollen flowers and nectar flowers according as they contain nectar or only pollen; or they may be divided into flowers with the nectar fully exposed, partly concealed, or deeply concealed.
Flowers pollinated by insects—value of the honeybee.
It is estimated that there have been described in the world up to the present time 132,600 different kinds of flowers. Kerner places the number of species pollinated by the wind at about 10,000; but this, un-doubtly, is an underestimate. But even if it is twice that number, there must be over 100,000 different species of flowers that are pollinated by insects. Insect flowers are usually bright-colored, often sweet-scented, and commonly yield nectar as well as pollen. The pollen, unlike the dry dusty pollen of wind flowers, is thickly be6et with teeth, spines, knobs, pits, and groves, which cause the grains to adhere together and to the bodies of the insects. Water is always hurtful to it, and there is an astonishing number of devices provided for its protection.