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Prothallus of the tree fern Dicksonia antarctica (note new moss plants for scale) Spore-bearing plants , like all plants, go through a life-cycle of alternation of generations . The fully grown sporophyte , what is commonly referred to as the fern , produces genetically unique spores in the sori by meiosis .
In most ferns, for example, in the leptosporangiate fern Dryopteris, the gametophyte is a photosynthetic free living autotrophic organism called a prothallus that produces gametes and maintains the sporophyte during its early multicellular development.
The haploid prothallus does not resemble the sporophyte, and as such ferns and their allies have a heteromorphic alternation of generations. The prothallus is short-lived, but carries out sexual reproduction, producing the diploid zygote that then grows out of the prothallus as the sporophyte.
The prothallus bears spherical antheridia (s.g. antheridium) which produce antherozoids (male gametophytes) and archegonia (s.g. archegonium) which release a single oosphere. The antherozoid swims up the archegonium and fertilize the oosphere, resulting in a zygote, which will grow into a separate sporophyte, while the gametophyte shortly ...
Land plants evolved from a group of freshwater green algae, perhaps as early as 850 mya, [3] but algae-like plants might have evolved as early as 1 billion years ago. [2] The closest living relatives of land plants are the charophytes, specifically Charales; if modern Charales are similar to the distant ancestors they share with land plants, this means that the land plants evolved from a ...
Closeup (10X magnification) of fibrous white prothallus. Verseghya thysanophora is pale yellow to greenish in colour, sometimes with blue or grey tones in shaded areas. It has a thin, leprose and sometimes patchy appearance. A visible, white and fibrous prothallus is often present with hyphae arranged in distinct radiating strands.
The lichen has a distinct prothallus—fibers of whitish fungal hyphae at the edge that lack photobiont, and which project beyond the thallus onto the growing surface. The prothallus is red to whitish in the inner part, red the in outer part. The surface of the thallus does not have a well-defined cortex, an outer layer of well-packed hyphae.
Megagametogenesis is the process of maturation of the female gametophyte, or megagametophyte, in plants. [1] During the process of megagametogenesis, the megaspore, which arises from megasporogenesis, develops into the embryonic sac, in which the female gamete is housed. [2]