Ch. 2: Flower and Fruit
From flower to fruit to seed: structure of a flower, pollination (self & cross), agents (bee, wind, water, bird), fertilisation, fruit types and seed dispersal — with full interactive animations.
Flower & Fruit lab
Watch bees pollinate, peel fruit layers, and see seeds fly. Every part of the chapter is animated.
Parts of a flower — tap a label
The flower is the reproductive shoot. It develops from a floral bud (terminal or axillary).
Petals attract insects. Sepals protect the bud. Stamens = male. Pistil = female.
- Essential whorls: androecium + gynoecium (make gametes)
- Non-essential: calyx + corolla (protect / attract)
- Complete flower = all 4 whorls (e.g. hibiscus)
Four floral whorls (outside → inside)
Epicalyx: extra outer leaf-like whorl (hibiscus). Naked flower: no petals/sepals (e.g. bougainvillea uses bright bracts).
Male (stamen) & female (carpel)
- Anther — head with pollen sacs
- Filament — stalk holding anther
- Pollen grains — carry male gametes (sperm cells)
- Stigma — sticky landing pad for pollen
- Style — tube connecting stigma → ovary
- Ovary — holds ovules (→ seeds) with ovum (egg)
Pollination — pollen transfer
Pollination = transfer of pollen from anther → stigma. Then sperm can reach the egg → fertilisation → zygote.
Pollen stays on the same flower or same plant. Little pollen waste · offspring similar · less genetic variety.
- Self → same genetics (less variation)
- Cross → more genetic diversity
- Cross uses wind, water, insects, birds
Agents of pollination — who does the job?
Entomophily · showy, scented flowers · sticky pollen
China-rose, sunflower
Anemophily · dull flowers · light smooth pollen · feathery stigma
Maize, grass, pine
Hydrophily · aquatic plants · flowers above / floating
Vallisneria, Hydrilla
Ornithophily · red/orange · lots of nectar
Canna, Bird of Paradise
Note: Maize has unisexual flowers on the same plant → monoecious. Male tassels at top, female ears lower down.
Life cycle animation: pollinate → fertilise → fruit → seed → plant
Attracts pollinators. Stamens make pollen; pistil holds ovules with egg cells.
Remember: Ovary → fruit · Ovule → seed · Fertilisation = fusion of male + female nuclei → zygote.
Fruit — ripened ovary
Pericarp = fruit wall (3 layers)
Fleshy · no stone · seeds in pulp
Kiwi, tomato, watermelon
Fleshy · central stone (pit)
Mango, plum, avocado
False fruit · thalamus fleshy
Apple, pear
Kitchen twist: brinjal, okra, tomato, bottle gourd are botanically fruits (from flower + seeds). Carrot/potato/spinach = vegetables (root/stem/leaf).
Seed dispersal — how seeds travel
Fruits protect seeds and help them spread so new plants don’t crowd the parent.
Light, wings, hair — drumstick, maple
Float on water — coconut, some aquatic plants
Eat fleshy fruit · hooks on fur
Pod bursts — milkweed, balsam
Topics in this chapter
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What is a flower?
Reproductive shoot from floral bud. Attracts pollinators. Makes gametes.…
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Parts and four whorls
Pedicel, thalamus, calyx, corolla, androecium, gynoecium.…
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Androecium (male)
Stamen = anther + filament. Pollen carries male gametes.…
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Gynoecium (female)
Stigma, style, ovary, ovules with egg cell.…
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Pollination
Self and cross. Transfer of pollen anther → stigma.…
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Agents of pollination
Insects, wind, water, birds — adaptations of flowers.…
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Fertilisation to fruit
Zygote forms; ovary → fruit; ovule → seed.…
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Types of fruits
Berry, drupe, pome. True vs false fruit. Pericarp layers.…
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Seed dispersal
Wind, water, animals, explosion. Fruit protects and spreads seeds.…
Philosophy check
- What is this civilization?
- Why was it advanced?
- How did cities work?
- Where do we still see these ideas?
- Exams — what will be asked?