A common plant question is, "Why doesn't my plant bear fruit?" Well, an answer might be that it needs pollinator or a pollinizer.
A pollinator is a separate plant which donates the pollen and a pollinizer is an agent or facilitator which carries the pollen - such as a beetle, moth, butterfly, ant or honeybee.
Pollen is the spores produced by the male part of a flower (the stamen). The carpel and pistil are a female flower's reproductive parts. The pistil receives the pollen and the carpel holds the eggs. When the eggs are fertilized, they become seeds. Sounds like basic birds and bees. The principal pollinating agents (pollinizers) are bees, moths, butterflies and birds. Some plants are not reliant on animals and employ nonliving agents, such as wind and water. Nature has developed strategies for spreading the pollen.
However, not all flowers have male and female parts. Some do, such as tomatoes, peas, apples and strawberries and they can self-pollinate. Pollinizers, wind or water might facilitate this. Other plants have separate male or female flowers. Typically, persimmons, kiwi and hollies (Ilex) are male or female. Cultivars might be named accordingly such as Ilex hybrid "Nellie R. Stevens" (female) a Chinese holly hybrid or Ilex "Jim Dandy" (male). The females need to be within 30 to 40 feet of the males for successful pollination.
Many plants operate on the "cash and carry" system by offering nectar, fragrance, and dazzling colors to attract birds and insects. The color and fragrance advertise to customers that food (nectar and pollen) are free to whatever steps inside. Pollen is loaded with protein and is eaten and carried back to the hives as a food reserve. Beetles pollinate magnolias, which don't offer nectar, but do produce copious amounts of pollen. The sugars in nectar also give food and energy to birds, butterflies and bees. As the agent is getting the "juice," it also is picking up the microscopic grains of pollen on its feet, legs and face. Then by going from flower to flower, field to field, the love is spread.
Floral parts might be simple, tubular, open, lipped or other variations. All of these designs facilitate the transfer of pollen and get it where it needs to go for fertilization. Melons, squash and cucumbers have male and female flowers on the same vine. Bees are the agent of choice in their pollinizing. If bees are not abundant, a Q-tip will work to transfer pollen. You might need to stick your face near the flowers to figure out which is which, but the pollen is borne on stalks. It is yellow.The female pistil is shaped like a bowling pin and is sticky on top.
Cross-pollination combines genetic material, produces stronger seeds and generally more plants reproduce by cross-pollination than self-pollination. Many fruit trees require pollen from the same species but a different variety. Apple, pears and blueberries are examples of this. Also, you need a good bloom overlap and spacing is important, too -- remember between 30 and 40 feet.