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Young sporophytes of the common moss Tortula muralis. 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 ...
The 'alternation of generations' in the life cycle is thus between a diploid (2n) generation of multicellular sporophytes and a haploid (n) generation of multicellular gametophytes. [ 17 ] Gametophyte of the fern Onoclea sensibilis (flat thallus, bottom) with a descendant sporophyte beginning to grow from it (small frond, top)
Some liverworts, such as Marchantia, have a cuticle, and the sporophytes of mosses have both cuticles and stomata, which were important in the evolution of land plants. [ 3 ] All land plants have a life cycle with an alternation of generations between a diploid sporophyte and a haploid gametophyte , but in all non-vascular land plants, the ...
Their life-cycle is strongly dominated by the haploid gametophyte generation. The sporophyte remains small and dependent on the parent gametophyte for its entire brief life. All other living groups of land plants have a life cycle dominated by the diploid sporophyte generation. It is in the diploid sporophyte that vascular tissue develops.
Mosses do not have seeds and after fertilisation develop sporophytes with unbranched stalks topped with single capsules containing spores. They are typically 0.2–10 cm (0.1–3.9 in) tall, though some species are much larger. Dawsonia, the tallest moss in the world, can grow to 50 cm (20 in) in height. There are approximately 12,000 species. [2]
In the more familiar seed plants, the haploid generation is represented only by the tiny pollen and the ovule, while the diploid generation is the familiar tree or other plant. [15] Another unusual feature of the liverwort life cycle is that sporophytes (i.e. the diploid body) are very short-lived, withering away not long after releasing spores ...
Sporophytes produce haploid spores by meiosis, that grow into gametophytes. Bryophytes are gametophyte dominant, [12] meaning that the more prominent, longer-lived plant is the haploid gametophyte. The diploid sporophytes appear only occasionally and remain attached to and nutritionally dependent on the gametophyte. [13]
Aglaophyton major. The stems of Aglaophyton were round in cross-section, smooth, unornamented, and up to about 6mm in diameter. Kidston and Lang [3] interpreted the plant as growing upright, to about 50 cm in height, but Edwards [1] has re-interpreted it as having prostrate habit, with shorter aerial axes of about 15 cm height.