Search results
Results From The WOW.Com Content Network
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 .
Many crustose lichens have a ring of unlichenised fungal hyphae at their edges. This fringe, known as a prothallus, may be black, white or the same colour as the rest of the thallus. [26] The term "crustose" derives from the Latin crustosus, meaning "crusted". [27]
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.
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.
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 ...
This means that a diploid generation (the sporophyte, which produces spores) is followed by a haploid generation (the gametophyte or prothallus, which produces gametes). Pteridophytes differ from bryophytes in that the sporophyte is branched and generally much larger and more conspicuous, and from seed plants in that both generations are ...
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.
alectorioid lichen An informal growth form category used for lichens that are fruticose, typically with beard-like thalli that are pendant or clustered; this group of features is characteristic of lichens now classified in the genera Alectoria, Bryoria, Oropogon, Pseudephebe, and Sulcaria.