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From this embryo the young sporophyte gradually develops and this may be supported and nourished by the gametophyte for several years. [6] They are usually arranged in spirals. Accessibility StatementFor more information contact us atinfo@libretexts.org. The embryonic sporophyte is nourished by food stored in the megaspore and transported through a massive foot. The prothallus consists of a short, tuberous central part from which a number of colourless, slender and cylindrical branches develop in an irregular fashion. As the name implies, clubmoss sporophytes (the spore producing form) look like mosses but they are generally bigger, reflecting the fact that they have vascular tissue, and they often have clubs or strobili, structures where spores are produced. Lycopodium: Habit and Habitat and Morphology - Biology Discussion Biology II Flashcards | Quizlet [1][4], Using the narrow circumscription of Lycopodium, in which it is one of nine genera in the subfamily Lycopodioideae, the Checklist of Ferns and Lycophytes of the World recognized the following species as of January2023[update]:[1]. Although the evolutionary origin of two kinds of spores (dimorphism) is unknown, the development of megaspores in living plants suggests that differences in nutrition in the two kinds of sporangia are significant. The sporangia of such primitive ferns are massive, with several layers of cellular walls, and produce an indefinite but large number of spores. Garden Guides | Lycopodium Life Cycle This is a question and answer forum for students, teachers and general visitors for exchanging articles, answers and notes. But opting out of some of these cookies may affect your browsing experience. In certain species of Lycopodium (e.g., L. lucidulum and L. selago) the sporophylls are similar to vegetative leaves. The gamete producing plant is often small, often only a few mm in size, rarely over a cm in size, and has an amorphous structure that produces small egg-producing archegonia and sperm producing antheridia. The sex organs (antheridium and archegonium) generally occur near the bases of the aerial lobes. The megaspores, accordingly, are much larger than microspores, although both contain stored food. All members of the group that exist today are small plants, typically less than 10 cm in height. There are also some intermediate types in between these forms. The higher C/N (Carbon/Nitrogen) ratio induces protocorm formation and eventually delay in differentiation of sporophyte. These branches bear sex organs and they are usually surrounded by glandular hairs called paraphysis. (iii) By the Formation of Adventitious Buds: The adventitious buds are formed near the base of the main stem and on separation from the main axis they are capable of forming new plants e.g., L. phlegmaria, L. reflexum. Therefore, in order to understand . As the sporangium matures, spore mother cells separate from each other and undergo meiotic division (reductional division) to form numerous spore tetrads (i.e., group of four cells produced by a meiotic division of a spore mother cell). The ratios are altered by changes in environmental conditions; for example, at certain temperatures (e.g., 32 C [about 90 F]), only male gametophytes develop from the spores of five species, whereas at 15 C (59 F) approximately 50 percent are male and 50 percent are hermaphroditic gametophytes. They are herbaceous, terrestrial plants or erect to pendent epiphytes. Each sporangiophore bears a number of fingerlike sporangia, which produce large numbers of thin-walled green spores. This cookie is set by GDPR Cookie Consent plugin. It does not store any personal data. Lycopodium clavatum ( Fig. The subterranean region always contains an endophytic fungus. The stems are densely covered with microphylls and are protostelic. Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. Rhizoids occur in the colourless subterranean (basal) region. The trilobed sporangia of the whisk ferns (Psilotum) are borne terminally on short lateral branches. l. Ibid.,tg . The sperms are released by breaking down the operculum at top. T he clubmoss sporophyte is a typical photoautotroph, using the energy of sunlight to synthesize carbohydrates from carbon dioxide and then using the carbohydrates as an energy source in cellular respiration and as building materials to synthesize a variety of biomolecules. In the simplest case, the sporophyte has a simple stem covered with numerous, moss-like leaves, each bearing a single large sporangium on its upper side. The spores are liberated as the older sporophylls decay. These cookies ensure basic functionalities and security features of the website, anonymously. The microsporangia can produce enormous numbers of microsporesas many as 1,000,000and the megasporangia give rise to 50 to 300 megaspores. The sporogenous tissue undergoes repeated mitotic divisions and ultimately gives rise to spore mother cells. In the genus Lycopodium, the club mosses, the sporangia are closely associated with the leaves. 17 July, 2017. The leaves are small and simple. You also have the option to opt-out of these cookies. The spores were also used as a type of lubricating body powder. The unisexual gametophytes are much like those of Selaginella, but the sperm are multiflagellate. (5) Roots and detached leaves of bulbils can also give rise to new individuals. Soon after this division, the exine ruptures along the triradiate ridge. It is not uncommon to find Lycopodium growing in arctic and temperate regions. Reproduction: Both Lycopodium and Selaginella reproduce via spores, but they differ in their sporangia placement. Historically, the spores were used as an early form of photography 'flash powder' as they can ignite explosively. Like all plants, clubmosses exhibit alternation of generations. Position of the sporangium and organisation of the strobilus. The archegonia are either short or long and embedded in the tissue of the gametophytes with their necks protruding upwards. In this type, the spore germination is delayed for a long time (one to many years), thus the prothallus has a longer lifespan. The antheridia vary in size, shape and number of spermatozoids and either project slightly or remain wholly embedded within the gametophytic tissue. Hence more than one type of prothalli may occur in the same species. The cookie is used to store the user consent for the cookies in the category "Analytics". The cells of the gametophyte contain fungal structures (hyphae) that probably are involved in some type of nutritional relation with the gametophyte. 7.31 C-D). This type is found in epiphytic species of Lycopodium (e.g., L. phlegmaria). The first division of the zygote is transverse to right angle to the long axis of the archegonium which produces an outer suspensor cell and an inner embryonic cell (Fig. Club moss leaves are called 'microphylls' to distinguish them from true leaves ( 'megaphylls' ) that have more extensive venation. Want to create or adapt books like this? These strobili are often separated from the vegetative body and are borne on slender stalks with rudimentary leaves. The cortex varies in thickness as well as in structure. Only one sperm eventually fertilises the egg that develops into the zygote. The most data on the gametophytes of Lycopodium clavatum, Lycopodium annotinum, and D. complanatum were accumulated by Bruchmann (1898, 1909, 1910), who investigated club mosses in the mountain forests of Thuringia, Germany, over a period of 30 years. L. selago. These tubercles on germination produce new sporophyte e.g., L. ramulosum, L. cernuum. Here the spore germination is immediate and the gametophyte grows for only one season. Most species produce above and/or below ground stems that run horizontally and send up vertically oriented branches. In more complex types, the sporophytes have much-branched stems whose lower leaves are sterile and act as foliage leaves, and this gradual sterilization process can be traced to more than one form where the sporophyte is distinctly differentiated into a vegetative region bearing foliage leaves, and a reproductive region bearing the sporophylls. These sporophylls usually become localized and aggregated to form cones or strobili, at the apex of the main stem or on lateral branches. The primary canal cell, by repeated divisions, forms 4-8 neck canal cells (exception, one neck canal cell in L. cernuum, 14 in L. complanatum). Reproduction in Lycopodium: Lycopodium reproduces both by vegetative and sexual methods. As cultivation of these . ADVERTISEMENTS: In this article we will discuss about the structure of Lycopodium with the help of diagrams. You may click on the image to view an enlargement. Here the prothalli are aerial but saprophytic in nature, grow on tree trunks below a coating of humus. This website uses cookies to improve your experience while you navigate through the website. This website includes study notes, research papers, essays, articles and other allied information submitted by visitors like YOU. In more advanced types of sporophytes, numerous furrows appear in the xylem cylinder so that the xylem breaks up isolated strands forming plate-like lobes or mesh-like mass, with included phloem bands. Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. The strobili are either stalked or sessile. Lycopodium (from Greek lykos, wolf and podion, diminutive of pous, foot) is a genus of clubmosses, also known as ground pines or creeping cedars, in the family Lycopodiaceae.Two very different circumscriptions of the genus are in use. Asexual reproduction. In most other ferns, the sporangia are smaller and long-stalked, with single-layered walls and a definite number of spores. In primitive ferns, such as Ophioglossum and Botrychium, the spores are borne upon a specialized axis, the fertile spike. Tree forms up to 35 m in height were common at the end of the Paleozoic, roughly 300 million years ago, and were important in forming deposits that are sources of coal and oil. The sporophylls of such strobili are different from vegetative leaves in size, shape, and colour. The rhizoidal cell disintegrates, while the large cell again divides by a vertical wall to form two cells. Share Your PPT File. Draw a neatly labeled diagram of chloroplast found in leaf, and its role in photosynthesis? Name the types of nitrogenous bases present in the RNA. In this approach, Lycopodium sensu lato has about 40 species. The group originated over 400 million years ago in the Paleozoic and the phylum is the oldest group of vascular plants that still has members today. The exine displays ornamentation that varies with the species (Fig. There are several means by which vegetative reproduction takes place: (1) Tips of lateral branches become flattened and with wing-like leaves, known as bulbils or gemmae annually fall to the ground, take roots and form new plants. Lycopodium is a homosporous pteridophyte i.e., it produces spores of equal size and shapes. The genus consists of about 180 species of which 33 are found in India. The Many Unexpected Jobs of the Clubmoss Spore - JSTOR Daily document.getElementById( "ak_js" ).setAttribute( "value", ( new Date() ).getTime() ); Terms of Service Privacy Policy Contact Us. They may be top-shaped with a convolute margin (L. clavatum) (Fig. : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.
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