Information AboutGymnosperm |
| CATEGORIES ABOUT GYMNOSPERM | |
| gymnosperms | |
| plant taxonomy | |
| sort31 gymnospermae | |
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Gymnosperms (Gymnospermae) is a name for a group of , in the Angiosperms ), but naked on the scales of a Cone or cone-like structure. The production of seeds distinguishes the gymnosperms (along with the angiosperms) from other members of the vascular plants. Thus together they are called Seed Plant s (Spermatophyta). Gymnosperms are Heterosporous , producing ''microspores'' that develop into Pollen grains and ''megaspores'' that are retained in an ovule. After fertilization (joining of the micro- and megaspore), the resulting embryo, along with other cells comprising the ovule, develops into a seed. The seed is a sporophyte resting stage. In early classification schemes, the gymnosperms (Gymnospermae) "naked seed" plants were regarded as a "natural" group. However, fossil finds suggest that the angiosperms evolved from a gymnosperm ancestor, which would make the gymnosperms a Paraphyletic group if all extinct taxa are included. Modern Cladistic s only accepts taxa that are Monophyletic , traceable to a common ancestor and inclusive of all descendants of that common ancestor. So, while the term gymnosperm is still widely used for non-angiosperm seed-bearing plants, the plant species once treated as gymnosperms are usually distributed among four groups, which can be given equal rank as divisions within the Kingdom Plantae . These groups are:
With regard to extant gymnosperms, molecular phylogenies of living taxa have conflicted with morphological datasets with regard to whether they comprise a monophyletic or paraphyletic group with respect to angiosperms. At issue is whether the Gnetophyta are the sister taxon to angiosperms, or whether they are sister to, or nested within, other extant gymnosperms. REFERENCES
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