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Most algae have dominant gametophyte generations, but in some species the gametophytes and sporophytes are morphologically similar . An independent sporophyte is the dominant form in all clubmosses , horsetails , ferns , gymnosperms, and angiosperms that have survived to the present day.
The microspores of both exosporic and endosporic species are free-sporing, distributed by wind, water or animal vectors, but in endosporic species the megaspores and the megagametophyte contained within are retained and nurtured by the sporophyte phase. Endosporic species are thus usually dioecious, a condition that promotes outcrossing.
Some species of red algae have a complex triphasic alternation of generations, in which there is a gametophyte phase and two distinct sporophyte phases. For further information, see Red algae: Reproduction .
Conocephalum is a genus of complex thalloid liverworts in the order Marchantiales and is the only extant genus in the family Conocephalaceae. [1] [2] Some species of Conocephalum are assigned to the Conocephalum conicum complex, which includes several cryptic species. [1]
The species Folioceros fuciformis and the genera Megaceros, Nothoceros and Dendroceros have short-lived spores with thin and colorless walls that appear green due to the presence of a chloroplast. [ 18 ] [ 19 ] In most species, there is a single cell inside the spore, and a slender extension of this cell called the germ tube germinates from the ...
In Common Smoothcap moss (Atrichum undulatum), the vibration of sporophyte has been shown to be an important mechanism for spore release. [15] In the case of spore-shedding vascular plants such as ferns, wind distribution of very light spores provides great capacity for dispersal. Also, spores are less subject to animal predation than seeds ...
Anthoceros species are host to species of Nostoc, a symbiotic relationship in which Nostoc provides nitrogen to its host through cells known as heterocysts, and which are able to carry out photosynthesis. [3] The Nostoc colonies are present on the lower ventral surface. They often grow in slime pores, mucilaginous groups of decomposed cells ...
One of the more than 100 species in this genus is the "slender riccia" (Riccia fluitans), ... The sporophyte of Riccia is the simplest amongst bryophytes. It consist ...