What is a moss - bryophyte. The bryophyte groups A moss is a flowerless, spore- producing plant - with the spores produced in small capsules. The introductory WHAT IS A BRYOPHYTE? The spore capsule, often with a supporting stalk (called a seta), is the sporophyte and this grows from the gametophyte stage. You will commonly see the statement that a moss gametophyte consists of leaves on stems. That statement is so close to the whole truth that it's no surprise it's so commonly used. When a moss spore germinates it first develops a protonema. The bryophyte groups What is a moss? A moss is a flowerless, spore-producing plant - with the spores produced in small capsules. The introductory WHAT IS A BRYOPHYTE?![]() This is a filamentous to sheet- like growth form, often with a strong resemblance to an algal colony or a fern prothallus. In almost all moss species, the protonemata are ephemeral, with the leafy- stemmed plants the persistent and dominant growth form. ![]() Is the sporophyte stage of a moss much larger than the gametophyte stage? Andy's Northern Ontario Wildflower Page Mosses and Lichens 'The important thing is not to stop questioning. Curiosity has its own reason for existing.' - Albert Einstein. Gametophyte and Sporophyte. Leonor C Boavida, University of California. The origin of the sporophyte in land plants represents a fundamental phase in plant evolution. Today this subject is controversial, and scarcely considered in textbooks and journals of botany, in spite of its importance. A gametophyte is a stage in the life cycle of plants and algae that undergo alternation of generations. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. Le sporophyte est le stade de la g. Cette phase du cycle de d But there are exceptions. In some species the protonema is persistent and the leafy part is ephemeral. The term gametophore is used for the stems- and- leaves part and the protonema and gametophore together make up the gametophyte. Now, as already noted, in almost all species the protonema is ephemeral and insignificant when compared with the leafy- stemmed growth. So the leafy- stemmed part is the gametophyte in the great majority of species. It now becomes clear why that fact is often generalized to the statement that the gametophyte in all mosses is leafy- stemmed. For more about the early development, see the LIFE CYCLE SECTION. In contrast to the case in mosses, a liverwort protonema is rudimentary. The aim of this page is simply to describe the features you can see in a moss - in both the gametophyte and sporophyte stages. You will see some, but by no means all, of the variety in moss gametophytes and sporophytes. This page gives an overview of the features found in mosses and there are links to more details on some of the topics. While the identification of mosses often requires the use of a microscope, you can learn a lot just by using your eyes and a handlens that magnifies 1. In the reference button you’ll find some books with colour photographs of Australian mosses. Looking through them will give you a good introduction to moss diversity. The following references are very useful for more detail about this great diversity, from the macroscopic view to the microscopic level. Much of the following information on this page has come from these books. Before going on it’s worth noting that you might confuse mosses with leafy liverworts (which also have a leaves- on- stems gametophyte stage). However, once you’ve read this page as well as the WHAT IS A LIVERWORT? For convenience, the distinguishing features of all the bryophytes are summarised on the page that lets you answer the question: WHICH BRYOPHYTE IS IT? Moss gametophytes While it may be true to say that a moss gametophyte has . There is a lot of complexity and variety in these ”stems and leaves. Stem colour varies from green to shades of brown, for example, Ptychomnium aciculare. Stems are often green when young, with chlorophyll in the cells. The mosses in the families Dawsoniaceae and Polytrichaceae provide striking exceptions to the general rule stated at the beginning of the previous paragraph. Within these families the stems are fairly firm, with the plants being upright and quite robust. In this photo of a Dawsonia you can see the brown stems quite clearly. Polytrichum or Dawsonia plants can be quite tall, with the free- standing stems of some species growing to over 6. Hence it is not surprising that people often mistake these mosses for herbaceous flowering plants. Though the stems in the Dawsoniaceae and Polytrichaceae are fairly firm, they contain no lignin and are not woody. Two growth forms - tufty and trailing There are essentially two growth forms for moss plants. In one the stems are basically erect, with just one upright stem per plant or with the initial erect stem producing some branches, depending on the species , giving the individual plant a tufty or shrubby appearance. In the other growth form the moss will have mostly trailing stems. If the stems cling to the substrate the overall appearance, to the naked eye, will be of a creeping plant but in some species they hang, almost curtain- like, from branches . Branches develop from surface cells in the originating stem and in most mosses branches are simple, single outgrowths from the originating stems. In Sphagnum you will see branches developing in fascicles. Within such a fascicle, some of the branches will be stout and spreading, while others are slender and drooping. If there is only a very rudimentary stem the plant will look like a bunch of leaves growing from just a single point. In genera like Polytrichum and Dawsonia the individual plants are typically just single stems, with branching rare. Amongst the upright mosses there are the so- called . In some cases, instead of branches in all directions, there'll be a fan- like spread of branches.
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