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Antheridia consist of a thin cellular layer that holds many sperm inside. Here, the diagram of a liverwort antheridium is shown. An antheridium is a haploid structure or organ producing and containing male gametes (called antherozoids or sperm). The plural form is antheridia, and a structure containing one or more antheridia is called an ...
Antheridia and archegonia occur on different gametophytes, which are then called dioicous. The moss Mnium hornum has the gametophyte as the dominant generation. It is dioicous: male plants produce only antheridia in terminal rosettes, female plants produce only archegonia in the form of stalked capsules. [26] Seed plant gametophytes are also ...
Oogonial cells may exist in a series along the filament, and so division may also occur in a series; resulting in each oogonium containing a single egg. [19] Production of an egg causes swelling of the cell wall. Antheridia are short and disk-shaped, containing 1 to 2 multi-flagellated sperm cells.
The green cells contain chloroplasts. Another characteristic feature of the genus is its parallel photosynthetic lamellae on the upper surfaces of the leaves. The leaves of most mosses are simply a single plate of cells, but those of Polytrichum have more highly differentiated photosynthetic tissue. This is an example of a xeromorphic adaption ...
The biflagellate sperm must swim from the antheridia, or else be splashed to the archegonia. When this happens, the sperm and egg cell fuse to form a zygote, the cell from which the sporophyte stage of the life cycle will develop. Unlike all other bryophytes, the first cell division of the zygote is longitudinal. Further divisions produce three ...
The green, photosynthetic part of the plant is technically a megaphyll and in ferns, it is often called a frond. New leaves typically expand by the unrolling of a tight spiral called a crozier or fiddlehead into fronds. [9] This uncurling of the leaf is termed circinate vernation. Leaves are divided into two types: sporophylls and tropophylls.
Structure of a plant cell. Plant cells are the cells present in green plants, photosynthetic eukaryotes of the kingdom Plantae.Their distinctive features include primary cell walls containing cellulose, hemicelluloses and pectin, the presence of plastids with the capability to perform photosynthesis and store starch, a large vacuole that regulates turgor pressure, the absence of flagella or ...
Plants are usually monoicous, and sexual reproduction is by antheridia and archegonia. Asexual reproduction occurs by spores, by fragmentation of the rosettes, and by formation of apical tubers. Spores are large (45 to 200 μ) and formed in tetrads. [2] The sporophyte of Riccia is the simplest amongst bryophytes. It consist of only a capsule ...