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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 ...
The plant body is a gametophyte.It consists of the main axis (differentiated into nodes and internodes), dimorphic branches (long branch of unlimited growth and short branches of limited growth), rhizoids (multicellular with oblique septa) and stipulodes (needle-shaped structures at the base of secondary laterals).
Diagram of archegonium anatomy. An archegonium (pl.: archegonia), from the Ancient Greek ἀρχή ("beginning") and γόνος ("offspring"), is a multicellular structure or organ of the gametophyte phase of certain plants, producing and containing the ovum or female gamete.
Spores that are buried underground, if reached by antheridiogen, can form gametophytes that reach the surface. Or, they form a small amount of antheridia, and the sperm produced can reach the female gametophytes above ground. The way in which the sex of each individual is determined is a form of environmental sex determination (ESD).
The antheridia (or globules [6]) and oogonia (or nucules [6]) are protected by a layer of sterile cells when mature; the oogonium is oblong in shape and consists of a single egg, while the spherical antheridium is packed with threadlike cells that produce spermatia. As a result, the Characeae have the most complex structure of all green algae.
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.
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 ...