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- Gymnosperms, also called Acrogymnospermae (1), are a group of seed-bearing plants (spermatophytes) with ovules on the edge or blade of an open sporophyll or ovuliferous scale (Fig. 1). 7eir closest extant relatives are the angiosperms, which have ovules enclosed in a carpel.
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Are gymnosperms spermatophytes?
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What is a Gymnosperm plant?
The term "gymnosperm" is often used in paleobotany to refer to (the paraphyletic group of) all non-angiosperm seed plants. In that case, to specify the modern monophyletic group of gymnosperms, the term Acrogymnospermae is sometimes used. The gymnosperms and angiosperms together constitute the spermatophytes or seed plants.
- Male Gametophyte
- Female Gametophyte
- Reproductive Process
A male cone has a central axis on which bracts, a type of modified leaf, are attached. The bracts are known as microsporophylls(Figure 2) and are the sites where microspores will develop. The microspores develop inside the microsporangium. Within the microsporangium, cells known as microsporocytes divide by meiosis to produce four haploid microspor...
The female cone also has a central axis on which bracts known as megasporophylls(Figure 3) are present. In the female cone, megaspore mother cells are present in the megasporangium. The megaspore mother cell divides by meiosis to produce four haploid megaspores. One of the megaspores divides to form the multicellular female gametophyte, while the o...
Upon landing on the female cone, the tube cell of the pollen forms the pollen tube, through which the generative cell migrates towards the female gametophyte through the micropyle. It takes approximately one year for the pollen tube to grow and migrate towards the female gametophyte. The male gametophyte containing the generative cell splits into t...
Apr 27, 2017 · As in all other vascular plants, gymnosperms have a sporophyte dominant life cycle (the sporophyte is the diploid multicellular stage, which comprises the body of the plant, i.e., a leafy tree). The gametophyte phase is relatively short, and sees gametes produced on the reproductive organs, which are usually cones.
Gymnosperms (“naked seed”) are a diverse group of seed plants and are paraphyletic. Paraphyletic groups do not include descendants of a single common ancestor. Gymnosperm characteristics include naked seeds, separate female and male gametes, pollination by wind, and tracheids, which transport water and solutes in the vascular system.
Among the numerous other gymnosperm species are many different reproductive processes. Some gymnosperms, for example, are dioecious, with microstrobili and megastrobili being borne on separate plants, as in junipers (Juniperus), plum yews (Cephalotaxus), yews (Taxus), and podocarps (Podocarpus).
- Hans Lambers
Lower vascular plants, such as club mosses and ferns, are mostly homosporous (produce only one type of spore). In contrast, all seed plants, or spermatophytes, are heterosporous, forming two types of spores: megaspores (female) and microspores (male).
Jul 31, 2022 · The life cycle of a gymnosperm involves alternation of generations, with a dominant sporophyte in which the female gametophyte resides, and reduced gametophytes. All gymnosperms are heterosporous. The male and female reproductive organs can form in cones or strobili.
