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Pollen

life science Maturity 9-11 Next article →

Pollen is a powdery substance produced by most seed plants for sexual reproduction.

Misc pollen colorized
Misc pollen colorized

While often thought of as just dust, each pollen grain is actually a highly reduced microgametophyte. This means the grain is a tiny organism that produces male gametes, or sperm cells. Pollen is essential for the survival of both angiosperms, which are flowering plants, and gymnosperms, such as conifers.

Tulip Stamen Tip
Tulip Stamen Tip

The transfer of this genetic material is a complex biological process. This process allows plants to create seeds and ensure the next generation of life.

The formation of pollen occurs in specialized structures. In angiosperms, pollen is produced in the anthers of a flower. In gymnosperms, it forms in the microsporangia of male cones. During development, fertile cells called archespores form within the anther. These cells undergo meiotic division, a type of cell division, to produce four haploid microspores.

Cactus flower pollen
Cactus flower pollen

Through a process called microsporogenesis, these microspores develop into mature pollen grains. They grow a tough outer wall and an inner wall to protect the vital cells inside.

Each pollen grain has a sophisticated double-walled structure. The inner wall is called the intine, which is a delicate layer made of cellulose. The outer wall is the exine, a very tough layer made of a biopolymer called sporopollenin.

RedbudPollen
RedbudPollen

This sporopollenin protects the genetic material from drying out or being damaged by solar radiation. The exine often features complex patterns, such as spines, warts, or net-like structures called reticulations. These markings are so unique that they can help scientists identify specific plant species. The exine is also so durable that it often survives in the fossil record.

Pollination is the process of moving pollen from the male part to the female part. This can happen through two main methods: wind or animals. Plants that rely on the wind are called anemophilous. These plants often produce massive amounts of lightweight pollen to increase their chances of success.

Pine releasing pollen into the wind in Tuntorp 4
Pine releasing pollen into the wind in Tuntorp 4

In contrast, entomophilous plants are insect-loving. They produce pollen that is heavier, stickier, and rich in protein to attract pollinators.

Apis mellifera flying
Apis mellifera flying

Insects like bees or flies visit flowers for food and accidentally carry the pollen to other plants.

Once a pollen grain lands on a compatible stigma, the next stage begins. The grain germinates and grows a pollen tube.

Pollen Tube
Pollen Tube

This tube acts as a pathway, growing down through the style toward the ovary. Inside the tube, the generative cell divides to form two sperm cells. These sperm cells travel to the tip of the tube to reach the ovule. Once they arrive, they can join with the female gametophyte to begin the creation of a seed.

Pollen grains vary immensely in size and shape. The smallest grains belong to the forget-me-not, measuring only 2.5 to 5 micrometers in diameter. In contrast, corn pollen is much larger, reaching about 90 to 100 micrometers.

Misc pollen colorized
Misc pollen colorized

Some gymnosperms, like pines and spruces, produce pollen with air bladders called sacci. These sponge-like structures increase buoyancy, helping the pollen stay aloft in the wind. Other grains may have various apertures, which are openings that allow the grain to swell or shrink based on moisture levels.

The study of pollen is a scientific field known as palynology. Because sporopollenin is so resistant to decay, pollen is frequently found in the fossil record. This makes palynology incredibly useful for several scientific disciplines. It helps paleontologists and paleoecologists reconstruct past environments and climates by looking at ancient plant life.

Jasper - Pollen storm - 20140624B
Jasper - Pollen storm - 20140624B

Archaeologists also use pollen to study ancient human sites. Even forensic scientists use pollen to help solve crimes by analyzing traces found at different locations.

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🖼️ Images & Media (11)
File:Misc pollen colorized.jpg
Misc pollen colorized.jpg
File:Pollen Tube.svg
Pollen Tube.svg
File:Coenocytic Tetrad.gif
Coenocytic Tetrad.gif
File:Tulip Stamen Tip.jpg
Tulip Stamen Tip.jpg
File:Cactus flower pollen.jpg
Cactus flower pollen.jpg
File:Jasper - Pollen storm - 20140624B.jpg
Jasper - Pollen storm - 20140624B.jpg
File:Apis mellifera flying.jpg
Apis mellifera flying.jpg
File:Episyrphus balteatus - head close-up (aka).jpg
Episyrphus balteatus - head close-up (aka).jpg
File:Diadasia Bee Straddles Cactus Flower Carpels close-up.jpg
Diadasia Bee Straddles Cactus Flower...
File:Pine releasing pollen into the wind in Tuntorp 4.jpg
Pine releasing pollen into the wind in...
RedbudPollen.TIF
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