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In mosses, the gametophyte is the dominant generation, while the sporophytes consist of sporangium-bearing stalks growing from the tips of the gametophytes Sporophytes of moss during spring In flowering plants, the sporophyte comprises the whole multicellular body except the pollen and embryo sac
Gametophyte of Mnium hornum, a moss . Dominant gametophyte (gametophytic). In liverworts, mosses and hornworts, the dominant form is the haploid gametophyte. The diploid sporophyte is not capable of an independent existence, gaining most of its nutrition from the parent gametophyte, and having no chlorophyll when mature. [21]
Moss leaf under microscope, showing gemmae and a hair point (40x) Moss gametophytes have stems which may be simple or branched and upright (acrocarp) or prostrate (pleurocarp). The early divergent classes Takakiopsida, Sphagnopsida, Andreaeopsida and Andreaeobryopsida either lack stomata or have pseudostomata that do not form pores.
The bryophyte gametophyte is longer lived, nutritionally independent, and the sporophytes are attached to the gametophytes and dependent on them. [5] When a moss spore germinates it grows to produce a filament of cells (called the protonema).
The gametophyte is unisexual and will produce either sperm or egg and not both at the same time. [13] Sperm is transported, often by water, to an archegonium located on the top of a female gametophyte shoot. Once an egg has been fertilized, it develops a diploid sporophyte structure which is composed of a foot, seta, sporangium, and operculum.
When a moss first grows from a spore, it starts as a germ tube, which lengthens and branches into a filamentous complex known as a protonema, which develops into a leafy gametophore, the adult form of a gametophyte in bryophytes. [1] Moss spores germinate to form an alga-like filamentous structure called the protonema. It represents the ...
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.
The diploid sporophyte generation of P. formosum matures in early summer and is short-lived. [5] The solitary sporophyte grows out of the female gametophyte, relying on it for energy and nutrients. It is anchored to the gametophyte by a foot, and has a stalk (seta) elevating a capsule in which spores will develop via meiosis. [17]