Tree and plant species will go all out to make sure their genes are passed on. This has lead to the development of various methods of pollination and seed dispersal, adopted by various tree species. Some of these methods may be very intriguing.

Plants evolve accordingly to make sure that pollination is effective. This goes hand in hand with their method of pollination. For example, for wind-pollinated plant species such as pine and grass, their strategy is to produce large amount of pollen so that the chance of pollen getting to the female is higher.

Others depend on animals to help pollinate their flowers. However not any animals can pollinate a specific plant species. Pollinators such as birds, butterflies, moths, bats and bees are able to pollinate certain types of plants. In this mutual relationship between flower and animals, each party benefits. The main purpose why some flowers only allow a specific pollinator is so that the chances of the pollen getting to the same species of flower are higher. For those flowers that allow a greater variety of pollinators to pollinate their flowers, they face the risk of having their pollen delivered to a different type of flower on the pollinator’s next visit.

Some species of flowers and pollinators has even taken a step further whereby the plant and the pollinator totally depends on each other. The term for this is coevolution, where there is a joint evolution between plant and its animal pollinator. An example of a coevolution would be the relationship between the yucca plant and the yucca moth. The female yucca moth lays her eggs in the flower and simultaneously pollinates the flowers. The caterpillars hatch within the seeds in the ovary. The flowers may lose some of their seeds, but it is worthwhile to ensure pollination.

For plants that requires animal pollinators, it is important that the plants:

1. Supply some reward for the pollinators (nectar, etc)
2. Advertise their presence
3. Have a way to implanting pollen onto the pollinator

 One interesting orchid has evolved such that it looks and smells like a female of a wasp species. Males of this wasp species emerge one week before the females, but the orchids are already blooming. When a male finds this orchid, it thinks it has just found a mate and tries to copulate and instead it ends up having pollens stuck to its body.

All flowers requiring a pollinator are designed to attract. For bee-pollinated flower, they tend to be mostly yellow with slight blue and an ultraviolet nectar guide. These flowers also tend to have a sweet scent, which the bees are able to smell. The nectars found in these flowers are usually situates in the far end of the flowers, at the end for a narrow tube. The position of the nectar is such that only a specific species of bees are able to reach it. Even so the bees are forces to struggle a bit to get to the nectar and during this slight struggle the pollens tend to adhere to the body of the bee.

The bucket orchid has a very interesting and complex method to fix pollen onto a bee. At the lower petal, there is a pot-looking structure which holds fluid is that dripped from gland above. The fluid is filled to a depth of 5mm. Orchid bees are attracted to the scent of this flower and attempt to collect oils from the gland area. However, as the sides of the flower are slippery, the bee slides into the fluid. The design on the pot is such that the bee is able to escape. However just as the bee tries to escape through a small exit tunnel on the side of the flower, the tunnel end is shut and the bee is trapped again. When this happens, pollens are fixed onto the bee’s back. A few minutes later, the bee is released and it flies off.

Butterflies, unlike bees are able to see most colours but are not able to smell. Thus butterflies tend to pollinate flowers are brightly coloured but are odourless. Butterfly pollinated flowers are usually found in clusters where it provide a landing ground for the butterflies.

Moths, like bats are nocturnal and, have a good sense of smell. Moth-pollinated flowers are also white or pale coloured so that it is more visible under the moonlight. Most moths pollinated flowers only open and release strong, sweet scent at night. These flowers also tend to be deep tubes that match the length of the moth’s tongue. The petals are usually flat and held backwards to allow the moths to get inside.

Birds like butterflies have good eyes but poor sense of smell. Hummingbirds are especially attracted to red. Thus flowers requiring birds for pollination are usually red or brightly coloured and lack odor. The petals are also held back to get it out of the birds’ way.

Fruits function to protect and disperse seeds whose function is to continue the next generation on plants. Plants adopt different methods to disperse their seeds.

Wind dispersed fruits are usually from emergent trees where their crowns are high up where there are wind. These fruits are light and have fluff or wings to carry them away as far as possible the wind can take them.

For water dispersed fruits, they are floatable and waterproof to prevent damage from the water.

For animal dispersed fruits,

1. some have structures to attach themselves onto animals, such as sharp barbs or hooks, or just being sticky
2. Some are small enough to be eaten and excreted by animals. The seeds are passed through the animal’s digestive tract unharmed and deposited in a moist nutrient-rich waste.
3. Have brightly coloured flowers and fruits like the ginger

Some plants resort to mechanical dispersal to release their seeds. Once dried and mature, the fruits of these plants pop out and release an explosion of seeds. Such trees include the rubber.

Fruits and seeds provide one of the most important concentrated resources to many invertebrates and vertebrate. Thus, to survive the seeds must be able to escape from predation. Some do so by being dispersed by specialized animals.