Carriage by Wind
Wind is a common carrier for pollen shifting the grains across distances both large and small. The scientific term for the distribution of pollen by the wind is anemophyly. Pollen that is designed to be distributed by the wind is lightweight and produced in large quantities to compensate for the loss of pollen that will never reach the plant stigmas for which it is intended. Plumes of airborne pollen can be visible to the naked eye at certain times of the year; these are the primary types of pollen that cause allergies in humans. Wind can carry and redeposit pollen within individual garden spaces or orchards or can carry the pollen over great distances. The ability of the wind to carry pollen far and wide is a key factor in the distribution of plants and the development of biodiversity and interbreeding in the plant kingdom.
Carriage by Insects and Pests
Entomophyly is the transfer of pollen by insects. Whether by bees, beetles, lady bugs, aphids, moths, spiders or one of many other crawling or flying insects, pollen is moved distances far and wide. Pollen is picked up by the insect as they traverse plants and collects on their feet, legs, wings and/or underbelly. Due to the sticky nature of pollen, it is picked up, secured to the insect and transferred anywhere in the insect's sphere of travel. The pollen can be released by rubbing or brushing transference, by the insect grooming itself or simply by dropping off over time. Pollen transference can be by nature's design with bees reaching into successive flowers to drink nectar and moving pollen from flower to flower. Pollen transfer can also occur more tangentially or by accident when an insect brushes up against a pollen sac when traversing the plant to munch on the leaves or to lay its eggs.
Carriage by Animals
Birds, bats, possums and even humans also play a role in picking up and distributing pollen far and wide. This again occurs with casual movement over or near the pollen source that allows the sticky substance to cling to almost anything it comes into contact with. Animals that groom themselves can gather pollen grains on their paws which is then transferred to surfaces they traverse and subsequent plants they touch. An animal can also consume fruit, flowers and leaves that carry pollen grains and the pollen will travel in their system until it is redeposited to the ground or on a plant or tree as part of the animal's waste.
Widespread commercial gardening, home and hobbyist gardening has brought about an increase in pollination by human hands and mechanized cultural practices. Orchid enthusiasts regularly hand pollinate their plants to breed species and create new hybrids. Home gardeners can intervene to ensure pollination of their best fruit trees. Commercial nurseries hand or spray pollinate to increase production creating mature fruiting and flowering plants more rapidly and at a lower price point.