Structures of insect and wind pollinated flowers and adaptations

A flower is the reproductive organ of a flowering plant. Most flowers contain both male and female parts, plus parts that attract pollinators and protect the flower.

Learn these parts and what each one does:

Part	Male / female	What it does
Stamen (anther + filament)	Male	Makes pollen
→ Anther	Male	Makes and releases pollen (pollen contains the male sex cells)
→ Filament	Male	The stalk that holds the anther up
Carpel (stigma + style + ovary + ovules)	Female	Receives pollen and contains the female sex cells
→ Stigma	Female	Receives the pollen (its top surface)
→ Style	Female	The stalk connecting the stigma to the ovary
→ Ovary	Female	Contains the ovules
→ Ovules	Female	Contain the female sex cells; become seeds after fertilisation
Petals	—	Attract pollinators (insects)
Sepals	—	Protect the flower while it is still a bud

Here is a labelled diagram of a typical flower cut in half:

Exam tip. Examiners love a "name the part / state its function" question. Learn the pairs: anther → makes pollen, stigma → receives pollen, ovary → contains ovules, petals → attract insects, sepals → protect the bud.

Pollination is the transfer of pollen from an anther (male) to a stigma (female). It is the first step that leads to fertilisation and the making of seeds.

Pollen cannot move on its own, so it needs a carrier. There are two main ways flowers get their pollen carried:

• Insect pollination — pollen is carried from flower to flower on the bodies of insects (such as bees and butterflies).
• Wind pollination — pollen is blown by the wind from one flower to another.

This is the key idea for spec 3.3: the flower's adaptations match its method of pollen transfer. An insect-pollinated flower is built to attract insects and stick pollen onto them; a wind-pollinated flower is built to release pollen into the air and catch pollen out of the air.

Exam tip. Define pollination precisely: "the transfer of pollen from an anther to a stigma". Do not confuse it with fertilisation (when the male and female sex cells join) — pollination happens first.

An insect-pollinated flower must do two jobs: attract an insect, then stick pollen onto it so the insect carries the pollen to the next flower. Every adaptation supports one of those jobs.

• Large, brightly coloured petals. These attract insects by being easy to see from a distance.
• Scent. A strong smell attracts insects towards the flower.
• Nectar. A sugary liquid that rewards the insect and tempts it to visit. The insect has to brush past the anthers to reach it.
• Sticky and/or spiky (sculptured) pollen. The pollen grains stick to the insect's body as it feeds, so they are carried away.
• Anthers held inside the flower. Positioned so the insect brushes against them and picks up pollen.
• Stigma held inside the flower, sticky. Positioned so an incoming insect rubs pollen onto it; its sticky surface holds the pollen.

So the whole flower works like a tempting "landing pad": colour and scent draw the insect in, nectar makes it stay, and the cleverly placed sticky anthers and stigma transfer the pollen as the insect feeds.

Exam tip. Always link each feature to its job — e.g. "large, bright petals to attract insects" or "sticky pollen so it sticks to the insect's body". A feature on its own (just "bright petals") usually does not score.

A wind-pollinated flower does not need to attract anything, so it "wastes" no energy on showy parts. Instead it is built to release lots of pollen into the air and to catch pollen out of the air.

• Small, dull (green/brown) petals — or none. No need to attract insects, so petals are not bright.
• No scent and no nectar. There is no insect to attract or reward, so these are not made.
• Lots of pollen. Wind is a "scattergun" — most pollen misses, so large amounts are produced to improve the chance of reaching another flower.
• Light, smooth pollen. Small, light grains are easily carried by the wind; a smooth surface helps them blow freely.
• Anthers hanging outside the flower. Loosely attached and held in the open air so the wind can easily blow the pollen away.
• Large, feathery stigma hanging outside. A big, branching, feathery shape gives a large surface area to catch pollen blowing past in the air.

So this flower is the opposite of the insect-pollinated one: dull and scentless, but with exposed dangling anthers spilling light pollen into the breeze, and feathery stigmas combing pollen out of the air.

Exam tip. The two features examiners reward most are light, smooth pollen (easily blown by wind) and a feathery stigma (large surface area to catch pollen). Always say why: "feathery stigma to catch pollen from the air".

The fastest way to remember spec 3.3 is to compare the two flower types feature by feature and notice that each difference comes back to how the pollen is carried.

Feature	Insect-pollinated	Wind-pollinated
Petals	Large, brightly coloured (attract insects)	Small and dull, or absent
Scent	Present (attracts insects)	Absent
Nectar	Present (rewards insects)	Absent
Amount of pollen	Smaller amounts	Large amounts (much is wasted)
Pollen grains	Sticky / spiky — stick to insects	Light and smooth — blown by wind
Anthers	Held inside the flower	Hang outside the flower
Stigma	Sticky, held inside	Feathery, hangs outside

A quick way to remember it:

1. Insect flowers show off (bright, scented, nectar) and stick pollen onto visitors.
2. Wind flowers are plain but dangle out in the breeze to throw and catch pollen.

Exam tip. A common 4–6 mark question is "Compare an insect-pollinated and a wind-pollinated flower" or "Explain how a wind-pollinated flower is adapted for pollination". Score full marks by giving several paired differences and linking each to the carrier (insect's body vs. moving air).