is haploid (fern) 7.101C). Each leaf is clearly differentiable into a petiole and a lamina, the venation being of the reticulate type. The highest chromosome number has been recorded in O. reticulatum where n = 631 +10 fragments. Ophioglossum palmatum. Bower (1896), however, consi­dered the spike of Ophioglossum as a septate sporangium, but this hypothesis was rejected by himself in 1911. Following views have been put forward by vari­ous workers to explain the morphological nature of the fertile spike of Ophioglossum: Bower (1896, 1908) suggested that it is a septate sporangium growing on the adaxial face of the sporophyll. Before sharing your knowledge on this site, please read the following pages: 1. The sporangia, however, are 0.5-3.0 mm. The sporangia are produced in two rows on a fertile segment that arises at the junction of the petiole and the sterile lamina (Fig. Life Plants Pteridophyta Pteropsida Ophioglossaceae. 7.92A). Large numbers of intercellular space occur between these cells. of the lamina shows an upper and lower epidermis (Fig. Spores are of same size and shape i.e., Ophioglossum is homosporous pteri­dophyte. Ophioglossum, the adder's-tongue ferns, is a genus of about 50 species of ferns in the family Ophioglossaceae.The name Ophioglossum comes from the Greek, and means "snake-tongue". Roeper (1859) considered that the spike rep­resents two basal pinnae of a compound leaf which have fused laterally to form the spike, the remaining pinnae fused to form a sterile blade. The neck barely protrudes out of the thallus. 7.94A). The development of a sporangium in Ophioglossum is of eusporangiate type. The length of the spike and the number of sporangia in each spike varies according to the species. The spore absorbs water and enlarges considerably. The first leaf and future shoot apex derive from the epibasai region of the embryo and the foot derives from the hypobasal region (Fig. Pl. Both the cells are embryonic. Gametophyte 4. Yeast: Origin, Reproduction, Life Cycle and Growth Requirements | Industrial Microbiology, How is Bread Made Step by Step? 7.99A-F). The epibasal cell develops into the stem and the first leaf. The archegonium is also initiated in the derivates of apical meristem (Fig. What are the three important components of biodiversity? But later (1911, 1926) he himself rejected this idea as it is not supported by the course of vascular supply from the petiole to the sporangia. Welcome to BiologyDiscussion! 7.100F). The size ranges from 2 mm to 6 cm in length and less than 1 mm to 3 mm in diameter. 7.92C). The central cell divides transversely into a primary canal cell and a primary venter cell. The Gametophyte 4. in diameter, sub-spherical and sunken within the leaf-tissue; these are also regarded by some to be fused forming a synangium along the margin of the leaf. It is especially common in lawns and cemeteries in the southeastern United States. Each antherozoid has a large basal vesicle and the terminal part bears numerous flagella (Fig. The annulus, a characteristic structure of other fern sporangia are absent in Ophioglossum. Ophioglossum definition is - the type genus of the family Ophioglossaceae comprising the adder's-tongues and having a solitary simple frond with netted venation and a terminal spike formed of two rows of coalescent sporangia. Many adventitious roots are borne on the underground stem. An archegonium is also developed from a single superficial cell of the gametophyte. There is considerable size variation in the gametophytes. 7.98A, B). Further develop­ment only proceeds if it gets infected with myc­orrhizal fungi. Ophiglossales is the only order under ferns showing subterranean gametophytes. Ophioglossum has two, viz. The root is the first and the prominent organ which arises near the middle of the embryo (from derivates of epibasai cell) and enlarges rapidly. Systematic Position of Ophioglossum: In modern classifications, Ophioglossum has been placed under the order Ophioglossales, a small group of eusporangiate ferns consisting of three living genera (Ophioglossum, Botrychium and Helminthostachys). 7.97A). (ii) Presence of collateral vascular bundle in the stem. The antherozoids are coiled and multiflagellate. Ophioglossum vulgatum L. Ophioglossum vulgatum L. is an accepted name This name is the accepted name of a species in the genus Ophioglossum (family Ophioglossaceae). Stomata are absent in the epi­dermis. The genus Ophioglossum is also known to produce millions of minute spores that develop into subterranean, mycoheterotrophic gametophytes. Its life history could be considered analogous to that of the orchids and pyroloids that produce dust seeds (Leake et al., 2008). What is the role of saliva in the digestion of food? 102(1), and the Veld & Flora Factsheets on the Classification of Life in vol. 7.101 A, B). Trisomy 21, or Down syndrome. Small adder’s-tongue. A T.S. Out of the 12 traces, 9 enter the sterile lobe (lamina) and do not anastomose, ‘whereas the rest 3 pass on to the base of the fer­tile spike where they divide and anastomose in the axial region (Fig. The first division of the zygote is transverse i.e., perpendicular to the long axis of the archegonium, giving rise to an epibasai and a hypobasal cell (Fig. (Double click on the photo to enlarge) Its life cycle is completed in about 7 … 7.96B). A number of vascular strands run longitudinal along the axis and from these strands many lateral branches develop which lead to the sporangia (Fig. Only one of these ultimate strands enters the sporangial wall, the others end blindly. 7.92A). The veinlets end blindly in the mesophyll which is a very distinct characteristic of Ophioglossum. There are two marginal rows of sporangia which are eusporangiate in their mode of development. Usually, all the spore mother cells are functional and eventually develop into spote tetrads. Bundle sheath is absent. The upper surface of the rhizome produces numerous leaves in an irregular spiral. 7.92A). Ophioglossum azoricum C. Press. Morphology of the Spike 3. The order contains this single family. Subsequent cell divisions are irregular and inde­finite. (v) Non-circinnate vernation of leaves even in the embryonic stage, (vi) Absence of sclerenchyma in any part of the plant body, and. Internally, the stem is siphonostelic as a rule, but occasionally the basal region of the stem may be protostelic with the upper part siphonostelic. In all the species investigated so far, the first divi­sion of the oos­pore is approxi­mately transverse, producing an up­per cell, the epibasal cell, and a lower one, the hypobasal cell. Choose from 500 different sets of biology plant life cycle flashcards on Quizlet. The pith is generally homogenous and composed of comparatively large, thin-walled, parenchyma cells, but in some cases (e.g., O. pendulum) small scattered patches of xylem may be found in the pith. One limb of the dichotomy becomes the fertile spike and the other sterile leaf. Later Holle (1875), Chrysler, (1910) and Bower supported this hypothesis. The factsheet in the June 2016 issue of Veld & Flora follows on from the factsheet in the March 2016 issue of Veld & Flora , vol. The outermost layer is epidermis which is single layered, suberised and devoid of any stomata. An androcyte mother cell divides to form two androcytes, each of which ultimately metamorphoses into an antherozoid or sperm. A convincing evidence for this interpretation has been provided by the vascular traces. One of the superficial cells functions as archegonial initial which, on periclinal division, forms an outer primary cover cell and an inner cell. Botany, Pteridophyta, Filicineae, Ophioglossum, Terms of Service Privacy Policy Contact Us, Notes on Botany for School and College Students, Copyright infringement takedown notification policy, Copyright infringement takedown notification template, Life Cycle of Psilotum | Pteridophyta | Botany, Life Cycle of Selaginella | Pteridophyta | Botany, Bryophytes: Chromosomes and Economic Importance | Bryophyta | Botany. The New Sporophyte. Common values are annual, biennial, and perennial. Occurrence and Distribution of Ophioglossum 2. 7.94B). Why does plant cell possess large sized vacuole? URI: Definition: the ratio of the dry mass of a leaf to its area show all records It remains surrounded by multi- layered wall of which the innermost wall layer functions as tapetum (Fig. TOS4. A T.S. The embryo is exoscopic in polarity i.e., the apical cell projects towards the neck of the archegonium. They show some similar characteristics like: (2) Stipules at the base of the petioles. At the very young stage, the primordium of spike diffe­rentiates on the lateral side into two vertical strips of cells in the epidermal layer. This listing contains taxa of plants in the division Pteridophyta, recorded from South Africa. This website includes study notes, research papers, essays, articles and other allied information submitted by visitors like YOU.