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Many club-moss gametophytes are mycoheterotrophic and long-lived, residing underground for several years before emerging from the ground and progressing to the sporophyte stage. [ 4 ] Lycopodiaceae and spikemosses ( Selaginella ) are the only vascular plants with biflagellate sperm, an ancestral trait in land plants otherwise only seen in ...
Some lycophytes are homosporous while others are heterosporous. [5] When broadly circumscribed , the lycophytes represent a line of evolution distinct from that leading to all other vascular plants , the euphyllophytes , such as ferns , gymnosperms and flowering plants .
Lycopodiaceae (homosporous lycophytes) split off from the branch leading to Selaginella and Isoetes (heterosporous lycophytes) about ~400 million years ago, during the early Devonian. The two subfamilies Lycopodioideae and Huperzioideae diverged ~350 million years ago, but has evolved so slowly that about 30% of their genes are still in ...
Chloroplasts (green discs) and accumulated starch granules in cells of Bryum capillare. Botanically, mosses are non-vascular plants in the land plant division Bryophyta. They are usually small (a few centimeters tall) herbaceous (non-woody) plants that absorb water and nutrients mainly through their leaves and harvest carbon dioxide and sunlight to create food by photosynthesis.
Heterospory evolved due to natural selection that favoured an increase in propagule size compared with the smaller spores of homosporous plants. [2] Heterosporous plants, similar to anisosporic plants [clarification needed], produce two different sized spores in separate sporangia that develop into separate male and female gametophytes.
Most non-vascular plants, as well as many lycophytes and most ferns, are homosporous (only one kind of spore is produced). Some lycophytes, such as the Selaginellaceae and Isoetaceae, [7]: 7 the extinct Lepidodendrales, [8] and ferns, such as the Marsileaceae and Salviniaceae are heterosporous (two kinds of spores are produced).
The life of a liverwort starts from the germination of a haploid spore to produce a protonema, which is either a mass of thread-like filaments or a flattened thallus. [ 18 ] [ 19 ] The protonema is a transitory stage in the life of a liverwort, from which will grow the mature gametophore (" gamete -bearer") plant that produces the sex organs.
In the homosporous families Lycopodiaceae and Huperziaceae, spores germinate into bisexual free-living, subterranean and mycotrophic gametophytes that derive nutrients from symbiosis with fungi. In Isoetes and Selaginella, which are heterosporous, microspores and megaspores are dispersed from sporangia either passively or by active ejection. [8]