ATTRACT VS ATTACK

How do flowering plants both coax pollinators and repel predators?

Flashy colours

The beauty and flamboyance we associate with some flowers didn’t occur by accident. Flowers are competing with each other to win over the birds, the bees and other important pollinators. As the most colourful parts of the flower are often the petals surrounding the nectar, they act as a visual target to guide pollinators.

Natural perfume

Each species produces its own unique scent. These are often dictated by their primary pollinators. Sweet-smelling flowers attract bees, while those aiming to attract beetles smell musty or rotten. This might not sound appealing to us, but each pollinator has a unique preference. Flowers with multiple pollinators can create different scents for each.

Pleasing shapes

Flowers grow in a variety of shapes and sizes. Some flowers, such as those in the pea family, have a lipped shape, with a curved upper lid and one underneath. The bottom petal serves as a platform for pollinators, and is a top choice for insects wishing to land and rest before entering the flower in search of nectar. Some daisies and other species have many tiny bud-shaped structures forming the head. These are covered in pollen and nectar, but have many tiny gaps, ideal for delicate butterflies to access.

Secret markings

Linear patterns can sometimes be seen on flowers. These might point towards the centre, being useful for guiding pollinators to the right area. Sometimes these markings can’t be seen by the human eye, but are visible to insects such as bees. These animals can see in ultraviolet light, and petals often hold secret markings that can only be seen through these eyes.

Deadly poison

Running from danger isn’t an option for a stationary flower. After pulling out the stops to attract a beneficial species, it needs a backup for when unwanted animals approach. Some flowers develop poisonous fruits or leaves to prevent herbivores from eating them, while others produce toxins upon being attacked.

Thorns and spines

Sharp, jagged thorns and spines, periodically spaced along the stem of a flower, are likely to put off any animal considering it as a snack. These are some of the most obvious signs of defence, working to stop danger before it arises. Spines are modified leaves, and are a predominant characteristic of cactuses. These are so sharp that they can easily draw blood, and protruding out adds extra defence from the Sun by creating areas of shade.

Idioblast detonation

An idioblast is a specialised cell that differs from the regular cells surrounding it. They can contain a range of materials, chemicals and minerals. Perhaps the most useful when under threat are those containing poison or needle-like crystals. When the cell is torn, the water pressure within the plant causes its contents to burst out and into the mouth of any animal whose bite caused the damage.

Death traps

Insects often live within plants, and some use flowers as food. Defence mechanisms are essential to stop flowers being eaten, and these can include the plant doing the eating itself. One example is the tropical pitcher plant. These flowering plants grow cup-shaped structures which act as traps for insects. When the insects fall in, they get stuck at the bottom in a puddle of digestive fluid, which kills them.