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02. The Flower

Key Terms

Prepared by: learnloophq@gmail.com

Last edited 25 days ago by Learn LoopHQ.

Chapter: 02. The Flower

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Pedicel: The stalk of flower.

Thalamus: The swollen structure in flower which bears all the floral whorls.

Sessile flowers: Flowers without pedicel.

Sepals: Small, green, leaf-like structures forming the calyx.

Calyx: The outermost whorl of flower formed of sepals.

Petals: Structures forming the corolla, often large and brightly coloured.

Corolla: The second whorl of flower formed of petals.

Stamen: The unit of androecium which is formed of anther and filament and produces pollen grains.

Androecium: The male reproductive whorl of flower.

Filament: The long, thread-like part of a stamen.

Anther: The bilobed, sac-like part of a stamen that contains pollen sacs.

Pollen grains: Yellow powdery structures formed in pollen sacs that contain male gametes.

Pistil/Carpel: The unit of gynoecium which is formed of ovary, style and stigma and produces ovules.

Gynoecium: The female reproductive whorl of flower.

Ovary: The swollen basal part of the pistil that contains ovules and matures into a fruit.

Ovules: Structures inside the ovary that contain female gametes (egg/ovum) and develop into seeds.

Style: The long, thread-like, middle part of pistil through which pollen tube grows.

Stigma: The swollen, knob-like, sticky tip of the style that traps pollen grains.

Accessory whorls: Calyx and corolla of a flower which help in pollination but do not take part in reproduction directly.

Essential whorls: Androecium and gynoecium of a flower which are reproductive organs and take part in fertilisation and seed formation.

Bisexual flowers: Flowers having both male and female reproductive organs (stamens and pistil), also called hermaphrodite flowers.

Unisexual flowers: Flowers having either male reproductive part (stamens) or female reproductive part (pistil).

Dioecious plants: Plants bearing male flowers in one plant and female flowers in another plant.

Monoecious plants: Plants bearing both male and female flowers on the same plant.

Solitary flower: A single flower on a twig at a specific position.

Inflorescence: The group or cluster of flowers borne on a twig or branch.

Complete flowers: Flowers having all four whorls: sepals, petals, stamens and pistils.

Incomplete flowers: Flowers having one or more whorls missing in them.

Pollination: The process of transfer of pollen grains from the anther to the stigma of a flower.

Self-pollination: Pollination that occurs in flowers on the same plant.

Cross-pollination: Pollination that occurs between flowers of different plants of the same species.

Pollinators: Agents like wind, water, insects, or animals that help transfer pollen grains.

Wind pollination: Transfer of pollen grains by wind.

Water pollination: Transfer of pollen grains by water.

Insect pollination: Transfer of pollen grains by insects.

Fertilisation: The fusion of male and female gametes to produce a zygote.

Fruit: A ripened ovary that consists of pericarp and seeds.

Pericarp (Fruit wall): Develops from the ovary wall and has three parts: epicarp, mesocarp, and endocarp.

Epicarp: The outer thin covering of the fruit.

Mesocarp: The sweet, fleshy middle layer of the pericarp in fleshy fruits.

Endocarp: The inner hard part of the pericarp.

Dry-fruits: Fruits in which the pericarp is dry, thin, and non-edible.

Fleshy fruits: Fruits in which the pericarp or some of its parts are soft and pulpy.

False fruits: Fruits in which the fleshy part develops from the thalamus of the flower, not just the ovary (e.g., Apple).

Seed: A fertilised ovule that develops after fertilisation and marks the beginning of new generation.

Seed coat: The protective outer covering of the seed.

Embryo: The baby plant in an inactive stage within the seed.

Radicle: The young root part of the embryo that grows into the root system.

Plumule: The feathery young shoot part of the embryo that gives rise to the shoot system.

Cotyledons: The seed leaves of the embryo, which may store food or be papery.

Endosperm: The tissue that stores food and provides it to the young plant.

Dicotyledonous (dicot) seeds: Seeds having two cotyledons.

Monocotyledonous (monocot) seeds: Seeds having only one cotyledon.

Dispersal of fruits and seeds: Distribution of fruits and seeds away from the parent plant.

Seed germination: The process by which the dormant or inactive embryo in the seed becomes active and grows into a seedling.

Imbibition: The process when a seed swells up by taking water, initiating germination.

Epigeal germination: A type of germination where the cotyledons come out of the soil, become green, and form first leaves.

Hypogeal germination: A type of germination where the cotyledons remain under the soil and do not form leaves.

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