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They include all forbs (flowering plants without a woody stem), grasses and grass-like plants, a vast majority of broad-leaved trees, shrubs and vines, and most aquatic plants. Angiosperms are distinguished from the other major seed plant clade, the gymnosperms , by having flowers , xylem consisting of vessel elements instead of tracheids ...
Megaspores are structures that are part of the alternation of generations in many seedless vascular cryptogams, all gymnosperms and all angiosperms. Plants with heterosporous life cycles using microspores and megaspores arose independently in several plant groups during the Devonian period. [2]
In angiosperms, the mechanism has been studied more extensively as pollen tubes in flowering plants grow very fast through long styles to reach the well-protected egg. There is great variation in pollen tubes in angiosperms and many model plants like petunia, Arabidopsis , lily and tobacco plants have been studied for intraspecific variation ...
Angiosperms are seed-producing plants that produce flowers and have enclosed seeds. [152] Woody plants, such as azaleas and oaks, undergo a secondary growth phase resulting in two additional types of tissues: wood (secondary xylem) and bark (secondary phloem and cork). All gymnosperms and many angiosperms are woody plants. [194]
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. The corresponding male organ is called the antheridium. The archegonium has a long neck canal or ...
Flower of Liriodendron tulipifera, a Mesangiosperm. Mesangiospermae is a clade that contains the majority of flowering plants (angiosperms). Mesangiosperms are therefore known as the core angiosperms, in contrast to the three orders of earlier-diverging species known as the basal angiosperms: Nymphaeales (including water lilies), Austrobaileyales (including star anise), and Amborellales.
In vascular plants, the diploid sporophyte has evolved as the dominant and visible phase of the life cycle. In seed plants and some other groups of vascular plants the gametophyte phases are strongly reduced in size and contained within the pollen and ovules. The female gametophyte is entirely contained within the sporophyte's tissues, while ...
In gymnosperms and angiosperms, the male gametophytes have been reduced to pollen grains, and in most of these, the antheridia have been reduced to a single generative cell within the pollen grain. During pollination , this generative cell divides and gives rise to sperm cells.