Pollination and Flower Anatomy

Pollination in Plants

• Angiosperms are advanced plants with well-developed flowers and fruits that surround seeds.
• Plants typically reproduce sexually.
• Sexual reproduction starts after pollination.
• Pollination is the transfer of pollen from the anther of one flower to the stigma of another flower (cross-pollination) or the same flower (self-pollination).

Parts of a Flower

• Pedicel/Peduncle: Flower stalk; supports the flower, often extends to form an inflorescence.
• Receptacle: Broadened base of the flower stalk.
• Sepal: Leaf-like structures that protect the developing flower bud. All sepals together compose the calyx.
• Petal: Colorful, often scented structures that form the corolla. They attract pollinators.
• Stamen: Male part of the flower, consisting of:
  • Filament: Stalk that supports the anther.
  • Anther: Pollen-bearing portion of the stamen.
• Pollen: A tiny structure with male reproductive cells.
• Carpel/Pistil: Female part of the flower, consisting of:
  • Stigma: Sticky top portion of the style, receptive to pollen.
  • Style: Structure connecting the stigma to the ovary.
  • Ovary: Enlarged portion containing ovules.
  • Ovule: Contains female gametes; develops into a seed after fertilization.

Flower Parts: Form and Function

• Sepals, petals, carpels, and stamens perform specific functions related to defense, attracting pollinators, reproduction.
• Calyx: Collective sepals. Protection of the flower buds.
• Corolla: Collective petals. Often bright colors, scent, and nectar production to attract pollinators.
• Stamen: Male reproductive structure. Anther produces pollen grains containing male gametes. Filament supports the anther.
• Carpel/Pistil: Female reproductive structure. Stigma is receptive to pollen. Style is the tube connecting the stigma and ovary. Ovary contains ovules which develop into seeds after fertilization.

Types of Pollination

• Insect Pollination: Flowers often have bright colors, strong scents, and nectar to attract insects. Anthers are usually exerted to better place pollen on the insect. Pollen adheres to the insect which then carries it to another flower.
• Bird Pollination: Often colourful, not scented, petals frequently fused into tubes allowing bird beaks to access nectar. Stamens located within the corolla tube. Birds carry pollen from the anthers to the stigma as they feed.
• Wind Pollination: Flowers have copious, lightweight, non-sticky pollen. They oftenlack a colorful calyx/corolla. Presence of large stigmas or well-exposed anthers to catch wind-borne pollen.
• Water Pollination: Aquatic plants with large, feathery stigmas to catch pollen. Male flowers may detach from the mother plant and float to pollinate other plants. Producing large numbers of pollen because much is lost to the water's currents.

Additional Notes

• Flowers of the same species often have the same type of pollination strategy.
• Flowers may be staminate (male parts only), carpellate (female parts only), or hermaphroditic (both male and female parts).
• Inflorescences are groups of flowers on a common stalk.
• Mammals (e.g., bats, mice) may also pollinate some types of flowers. Often have strong scents, large flowers, and tube-shaped petals, blooming at night.