Explain the life history of lycophytes, Biology

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Explain the Life History of Lycophytes?

Lycophytes have two separate and distinct generations in their life history that alternate with each other. The gametophyte stage is tiny, colorless, and grows in and on the soil. It is haploid (1n) in terms of chromosome number, and produces sexual reproductive structures called male antheridia and female archegonia. Water must be present for sperm to fertilize an egg in an archegonium, and as such, the sperm have flagellae. Upon fertilization, the embryo, which is now 2n, and the beginning of the sporophyte generation, develops within the archegonium on the gametophyte generation.

Eventually, the sporophyte develops into an independent generation and produces the green leafy plants that we recognize as a lycopod. The leaves formed are called microphylls. Specialized microphylls become sporophylls, bearing sporangia. When clustered tightly together in a modified cone structure, they are called a strobilus, plural - strobili. The sporangium undergoes meiosis to form 1n, or haploid, spores. These spores upon release, germinate into the tiny gametophyte stage to repeat the cycle.

 


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