Flower dissection and hand pollination of rapid-cycling brassicas · Concept Studio

The idea

A flower's parts are organised for pollen transfer and fertilisation, and moving pollen by hand between chosen parents is the basis of artificial pollination in plant breeding.

What you need

Large flowers for dissection that a NSW school can buy or pick in season (for example hibiscus, lily, snapdragon or gladiolus), 1 per pair; the SAPS dissection method is written for horse chestnut, which is uncommon in Australia, so the same order of whorls is followed on the flower to hand
Rapid-cycling brassica plants in flower (grown from seed following the SAPS planting and care sheets, about 14 days to flowering under continuous light), 2 per group
Hand lens or stereo microscope; forceps; scalpel on a white tile; fine paintbrush or a dried bee on a stick; labels; slides and microscope for pollen

How to do it

Dissect the large flower from the outside in, removing sepals, petals, stamens and finally the carpel; lay the parts out in order and draw them labelled.
Cut the ovary open lengthwise and count the ovules; dust pollen onto a slide and view at 100x.
On the brassica plants, choose a donor flower and touch its anthers with the brush, then transfer the pollen to the stigma of a flower on the other plant; label the pollinated flower with the date and parents.
Leave some flowers unpollinated and bagged as controls.
Over the following two to three weeks record which flowers form pods and, at maturity, count seeds per pod for pollinated and control flowers.
Relate the hand-pollination step to how breeders make a chosen cross.

What you should see

The dissection yields the four whorls with stamens outside the carpel; pollen grains are visible as many small spheres. Hand-pollinated brassica flowers swell into pods within days and set seed, while bagged unpollinated flowers wither or set few seeds because brassicas are largely self-incompatible. The learner knows it worked when pollinated flowers set pods and the controls do not.

What changes

What you change: pollination treatment (hand-pollinated with pollen from another plant, or bagged and unpollinated)
What you measure: pods formed and seeds per pod
What you keep the same: plant age and growing conditions
flower position
timing
brush technique

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

Pollen is the plant's seed; pollen carries the male gametes and the seed forms after fertilisation.
Flowers always self-pollinate if left alone; many plants reject their own pollen.
Artificial pollination changes the plant's genes directly; it only chooses which gametes meet.

Safety card

Low riskLearners carry it out

Hazards

Scalpel cuts
Pollen allergy
Plant sap irritation

Controls

Cut on a tile away from the body
Learners with pollen allergy handle the dissection only
Wash hands afterwards

Note

No hazardous chemicals; RiskAssess (https://www.riskassess.com.au/).

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

Biology Stage 6 Syllabus (2017), current: Year 11 taught to the end of 2026 and Year 12 to Term 3 2027BIO12-12 BIO12-13 BIO11/12-4 BIO11/12-7
Biology 11–12 Syllabus (2025), Year 12 focus area Biodiversity; new syllabus not yet taught: Year 11 from Term 1 2027, Year 12 from Term 4 2027BI-12-03
Biology 11–12 Syllabus (2025), Year 12 focus area Biotechnology; new syllabus not yet taught: Year 11 from Term 1 2027, Year 12 from Term 4 2027BI-12-04
Biology 11–12 Syllabus (2025), Year 12 Working scientifically; new syllabus not yet taught: Year 11 from Term 1 2027, Year 12 from Term 4 2027BI-12WS-04 BI-12WS-07
Australian Curriculum v9No Australian Curriculum v9 code is listed.

Sources

The pages the author read to write this activity.