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How does a fern spore develop into a gametophyte?
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plant
Grandidier's baobas (Adansonia grandidieri) in Madagascar.
When a fern spore lands in a suitable, moist environment, it undergoes germination to develop into a gametophyte, commonly known as a prothallium.31
The development process typically follows these stages:
- Emergence: As the spore wall cracks, a nongreen rhizoid emerges to anchor the plant to the surface, alongside a green mother cell that initiates further growth.2
- Initial Growth: In most homosporous ferns, the gametophyte begins as a single filament of cells.2
- Maturation: Under optimal lighting, the structure expands into a two-dimensional, heart-shaped sheet of cells that is generally one cell layer thick. A growth zone, or meristem, develops in an apical notch, flanked by prothallial wings.21
- Sexual Phase: The mature prothallium, usually measuring 2 to 8 mm in length, produces male (antheridia) and female (archegonia) sex organs on its undersurface.21
Once fertilization occurs and a new sporophyte embryo is established, the parental gametophyte typically withers and dies.31