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Ophioglossum.pptx member of pteridophytes

The document provides an overview of the class Ophioglossales within the Pteropsida, focusing on the genus Ophioglossum, commonly known as adder's-tongue ferns. It details their classification, habitat, reproductive cycle, and unique anatomical features, including the high chromosome numbers found in various species. The document also highlights the distribution of Ophioglossum species and their ecological significance.

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1 Course Title: Diversity of Vascular plants Course Code: BOTN 3113 Dr. Aasma Tufail Assistant Professor, Department of Botany, Division of Science & Technology, University of Education, Lahore Lecture # 11 Pteropsida Ophioglossum
Pteropsida Ophioglossum adder's-tongue ferns, Dryopteris wood fern, male fern, or buckler fern Azolla/Marsilea Aquatic fern or water clover
Ophioglossum, the adder's-tongue ferns,
Classification • Pteropsida Class Sub- Class • Ophioglossales Order • Ophioglossaceae Family Eusporangiatae
Habit and habitat The name Ophioglossum comes from the Greek word and means "snake-tongue" It has almost 25-45 species in world wide distribution Their cosmopolitan distribution is mainly in tropical and subtropical habitats like between Africa and south America, Northern hemisphere in Europe, temperate Asia e.g. O. vulgatum. In Austraila, Spain Purtagal e.g. Ophioglossum lusitanicum It is terrestrial and grow in soil rich in humus About dozen species recorded from India. The plant grows from a central, budding, fleshy structure with fleshy, radiating roots.
Important species of Ophioglossum Ophioglossum reticulatum Ophioglossum vulgatum
Sporophyte or plant body •The sporophyte is differentiated into a sub­ terranean rhizome with roots •and spirally arranged leaves bearing sporangiferous spike
Sporophyte description • Terrestrial or epiphytic herb, ever green but commonly arising from rhizome. • Rhizome vertical or shortly horizontal • Roots are fleshy but without root hairs but some time proliferious • Leaves commonly single, some time up to six • Sterile lamina (trophophore) born on a stipe, simple, entire, glabrous, lacking a midrib, 1.2-250 mm long. • Fertile spike arising at or just below the base of the lamina or born centrally on lamina, comprising two rows or up to 90 pairs of sporangia fused laterally on a fertile spike Born on a stalk
Reproduction life cycle of Ophioglossum • Vegetative (by means of adventitious buds formed on roots e.g. in O. pen­ dulum, O. vulgatum, O. reticulatum, O. nudicaule and O. aitchisonii ) • Asexual by means of spores (Sporophytic generation) Spores are of same size and shape i.e., Ophioglossum is homosporous pteri­ dophyte. • Sexual by means of antheridia and archegonia (Gametophytic generation)
Spore-Producing Organ: •The spores are present in sporangia. •The sporangia are produced in two rows on a fertile segment that arises at the junction of the petiole and the sterile lamina
Structure of sporangium • Each mature sporangium is spherical or oval in shape and remains embedded in the tissue of the fertile spike. Oval in shape. • The size ranges between 0.5 to 3 mm in diameter. • It remains surrounded by multi- layered wall of which the innermost wall layer functions as tapetum • The sporangial cavity is filled with many spore mother cells. • Number of spores ranges 1500 to 15,000 spore mother cells
Dehiscence of the Sporangium: • Sporophore with dehisced sporangia Sorus Eusporangia - Thick walls - not stalked - many spores - initiated by many cells
Gametophyte generation
Antheridia development
Archegonia
Development of embryo
Chromosome Number of Ophioglossum: •The chromosome number of Ophioglossum is generally high, although there is no uniformity in the basic number. •O. pusitanicum has n = 125-130, while in O. vulgatum n = 250-260. The highest chromosome number has been recorded in O. reticulatum where n = 631 +10 fragments.
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). They do not have any early fossil record. The plant is unique in having sporangia borne on a fertile spike that projects from the leaf near the junction of the lamina and the petiole. • https://www.youtube.com/watch?v=4V4bdzGS7ys
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