A fern grows not from seed, but from a single-celled spore, initiating a two-stage life cycle.
Here's a breakdown of the fern's unique growth process:
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Spore Release: The mature fern (sporophyte) releases spores, typically from the underside of its fronds (leaves).
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Gametophyte Development: If a spore lands in a suitable moist environment, it germinates and grows into a small, heart-shaped structure called a gametophyte (also known as a prothallus). This is the sexual generation.
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Fertilization: The gametophyte produces both male (sperm) and female (egg) reproductive structures. Sperm require a film of water to swim to the egg for fertilization.
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Sporophyte Development: After fertilization, the resulting embryo grows into the sporophyte – the fern plant we recognize with its roots, stem, and fronds. The sporophyte is the asexual generation. The gametophyte nourishes the young sporophyte initially, but eventually, the sporophyte develops its own root system and becomes independent.
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Maturity: The sporophyte matures and eventually produces its own spores, completing the cycle.
In essence, the fern's growth involves an alternation of generations, shifting between a sexual (gametophyte) and an asexual (sporophyte) phase. This distinguishes it from flowering plants that reproduce solely through seeds.
