The relationship between insects and flowers

Clever adaptation of insects and flowers;

In the process of long-term natural selection, the relationship between insect-borne flowers and insect life has been inextricably linked. The color and structure of flowers are very cleverly adapted to the activities of insects.

In the northern hemisphere, the flowers of plants are often yellow, white, purplish red or blue, because the general insects here have poor ability to distinguish bright red. Near the tropics and subtropics, flowers are often bright red, because there are butterflies and hummingbirds who are good at distinguishing bright red. As for the night, because moths are active frequently, the flowers that bloom at night are mostly white and have a strong fragrance. Dark yellow or crimson flowers smell rotten, and their visitors are mainly flies.

In plants pollinated by insects, pollination is usually done by insects. Insects look for flowers and collect honey from them, so that pollen sticks to them. When they visit other flowers, some pollen will be scattered on the stigma of these flowers to help plants complete pollination. In this process, insects get food and flowers get pollination, which are mutually beneficial and complementary.

It will be very interesting to observe the scene of marsupial bees collecting honey from sage flowers. Salvia is a labiatae plant. It has a labial corolla with a pistil and two stamens under the upper lip. The stamens are T-shaped and have a unique structure, just like two levers arranged side by side at the entrance of the flower tube. When the honeybee stepped on his lips and put his head into the flower tube to eat honey, the lower end of the T-shaped stamen was pushed inward by the insect's head, and the upper end drooped due to leverage, just hitting the anther on the back of the honeybee, so that the pollen was scattered. When this bee flies to another flower to collect honey, as soon as its back touches the stigma of the drooping pistil, it will pass the pollen to the stigma of that flower by the way.

The corolla structure of snapdragon is also very interesting. The upper and lower lips of its corolla are closed, and the pistil and nectar are sealed in the tube. In this case, if the insect is too small to step on the flowering lower lip, it can't get in; If it's too big, you can't get in even if you step on your lower lip. Only those insects as big as bees can step on their lower lips and enter the flower tube to suck honey and pollinate.

Sometimes, an insect collects nectar from only one plant. Chun Mei bees only suck the nectar of Chun Mei grass, while another kind of bees only collect the nectar of Haishou flower. Because plants and insects have such a close relationship, there are many plants and their main pollinators, and their geographical distribution is almost the same. Red clover, for example, can only blossom and not seed when it is first planted in New Zealand, and it will not start to seed until 1885, when pollinated marsupials are brought in. There is an orchid in Madagascar. The flower tube is one foot long, and the nectar is hidden deep in the base of the flower tube. Later, it was found that there was a moth with a kiss of more than 30 centimeters to pollinate it.

In the flowers of many plants, there are some special structures that can effectively ensure the pollination of plants. Nectar may be located in the depths of flowers. In order to reach it, insects must pass through the stigma of stamens or pistils to complete pollination. There is a plant called Aristolochia, whose petals are born together and become a long bobbin, just like a bottle with a long neck. Both pistil and nectar are at the bottom of this "bottle", and the hair inclined to the bottom grows in this section of the bottleneck. Aristolochia is a flower whose pistil matures first, and the pistil matures two or three days earlier than the stamens. When the pistil matures, the nectar at the bottom of the bottle secretes sweet nectar. In order to eat nectar, bugs will crawl into the bottom of the flower tube along the hair. However, when it is full, because the hair inclined downward from the bottleneck prevents its way out, the bug will run around in panic and send the pollen from it to the stigma, which meets the requirements of cross-pollination of Aristolochia. After fertilization, the hair at the bottleneck changes, withers and falls off. At this time, the stamens are also mature, and the scattered pollen is attached to the bug; So, the worm took the pollen from this flower and flew to another flower to pollinate.

The relationship between yucca and yucca moth is particularly delicate. The style of Yucca is hollow, forming a cylinder, and the stigma is at the lower part of the cylinder. Therefore, only when the pollen reaches the bottom of the style can pollination be carried out. Yucca moth is the only insect that can pollinate it. When yucca blooms, yucca moth flies into the ovary from the catheter, eats a hole in the ovary wall and arranges eggs in the ovule of the ovary. In this process, it also transfers the collected pollen to the hollow style and reaches the stigma. The eggs arranged in the ovary feed on seeds after hatching, but there are many seeds of yucca, so it will not hinder the reproduction of yucca if the larvae eat part of them. Then, yucca silkworms spin silk and make cocoons with the silk. When yucca blooms again in the future, the moth just matures and flies to the ovary of yucca to lay eggs.

The structure of Phalaenopsis grandiflora is also very special. The end of its lips became a bathtub-like spoon, which was filled with the juice secreted by two appendages at the bottom of its lips; There is also a cockscomb process on the lip. Bumblebees, who like to bite cockscomb, try to climb out of the spoon, hit a plate with pollen, and then climb out of a hole between the spoon and the style when they compete for food and roll into the spoon. Bumblebee will never learn from this drowning, but almost immediately return to its gnawed comb, fall into the bathtub again and climb out of the same orifice. In this way, when it comes out again, it will insert pollen into the stigma. Sometimes, you can even see many bumblebees gathering in a line and constantly passing through that specific hole in the big flower helmet orchid.

In nature, this phenomenon of forcing insects to pollinate flowers can also be seen in primroses, litchi flowers and platycodon grandiflorum. For example, there is a groove in the flowers of plants such as radish and water spinach, which allows insects to sink their feet and stick to pollen, which is also a special structure for insect pollination.