What is the subtle relationship between flowers and insects?

Insect-borne flowers attract insects with beautiful perianth, fragrant smell and sweet honey juice, and at the same time form an adaptive relationship with pollinators in shape and structure. The size, structure and nectary position of flowers are closely related to the size, shape, structure and activity of insects.

For example, Aristolochia of Aristolochiaceae is a common medicinal plant. Its flower tube is very long, with pistils, stamens and nectaries at the base, and hairs inclined to the base at the upper part of the flower tube. Its pistil ripens two or three days earlier than the stamens. When the pistil is ripe, the bug crawls into the base of the flower tube to suck honey. When it is full of honey and tries to quit, because the hair in the flower tube grows downwards, the bug crawls around for a while, so that the pollen of another Aristolochia flower carried by the bug sticks to the stigma of this flower, and cross pollination is completed. After two or three days, the stamens are ripe, the insects are still drilling in the flowers, and the scattered pollen sticks to the insects. Interestingly, at this time, the hair in the flower tube contracted, and the "imprisoned" bug climbed out covered in pollen. It flew to another Aristolochia flower to send pollen to it.

Another example is the snapdragon of Scrophulariaceae, also called bibcock flower, which is a lip-shaped corolla, but the upper and lower lips of the lip-shaped corolla are always fastened and closed. The pistil, stamen and nectary are all locked in the tube. Under this structure, if the insect is too small, it can't step on its lower lip and enter the flower. If the bug is too big, you can't get in even if you open your lower lip; Only medium-sized insects like bees can open their lower lips and enter the corolla tube. When the bee probes into the corolla tube, its back rubs the anther and stigma. Because the anthers are on both sides and the stigma is in the middle, the pollen of the same flower will not be brought to its own stigma by bees, but the pollen of another snapdragon flower brought by bees just rubs against the stigma of this flower, thus completing cross pollination.

Sage in Labiatae is more interesting. It is a lip-shaped corolla with pistil and two stamens under the upper lip. The connective of the two stamens extends into a small lever and is juxtaposed at the entrance of the corolla tube. When bees enter the depths of the corolla tube to suck honey, they will inevitably touch the lever, the stamens will droop because of the lever, and the anthers will just touch the back of the bees, and the pollen will be scattered on it. When a bee visits another sage flower, its back touches the hanging stigma, and then it spreads pollen to the stigma to complete pollination.

There is an orchid in the tropics. Its lower lip petals are like a bathtub, which is often filled with clear water. There is a narrow tunnel in the bathtub. Stamens and pistils are born at the top of the tunnel. When the wasp got into the flower and sucked honey, it slipped and fell into the bathtub. When it got up wet and ran away, it had to climb out of the tunnel and let the wasp smear the pollen from another orchid on the pistil of this flower, and at the same time let the wasp take the pollen away from this flower.

The above example tells us that different kinds of insects spread pollen to specific flowering plants and use the pollen of these plants as their own nutrition. In this process of mutual benefit and mutual adaptation, their respective races have been multiplied.

The relationship between flowers and insects is not formed overnight, but the result of adaptation of plants and insects in the long-term biological evolution.