Flowering Plant Reproduction: Asexual & Sexual Strategies in Angiosperms

Flowering plants (angiosperms) dominate the plant kingdom with 250,000–400,000 species. Their reproductive success stems from two strategies: asexual (vegetative) propagation and sexual reproduction via flowers.

Flower Anatomy

A typical flower contains four whorls: sepals (calyx), petals (corolla), stamens (androecium – male), and carpels (gynoecium – female). Some species have separate male and female flowers.

Asexual Reproduction

New genetically identical individuals arise from vegetative parts—roots, stems, leaves, rhizomes, bulbs, tubers, runners—without fertilization. This vegetative propagation allows rapid colonization and is widely used in horticulture (cuttings, division, layering).

Sexual Reproduction

1. Gamete Formation: Anthers produce pollen grains (male gametophytes, 2 cells). Ovules develop embryo sacs (female gametophytes, 7 cells/8 nuclei).
2. Pollination: Pollen transfers to stigma (wind, insects, birds).
3. Fertilization: Pollen tube grows down style to embryo sac. Two sperm cells arrive: one fuses with egg → zygote (2n); the other fuses with two polar nuclei → triploid endosperm (3n). This double fertilization is unique to angiosperms.
4. Seed & Fruit Development: Zygote becomes embryo; endosperm nourishes it; ovary matures into fruit.

Life Cycle

Angiosperms alternate between a dominant diploid sporophyte (the plant) and a reduced haploid gametophyte (pollen/embryo sac). Sexual recombination generates genetic diversity, driving adaptation and speciation.