Major Groups of Plants - Vascular Plants

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About the Vascular Plants - one of the four major group of plants

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Major Groups of Plants Seedless Vascular Plants

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M ajor Groups of Plants Major Groups Bryophytes Seedless Vascular Plants Gymnosperms Angiosperms Mosses Ferns Conifers Flowering plants

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Seedless Vascular Plants Evolved from moss-like plants. Characteristics : F irst plants to grow to large size and away from open water T he presence of a vascular system A dominant sporophyte stage Dispersal through spores ferns , whisk ferns, club mosses, horsetails Divisions of Seedless Vascular Plants Pterophyta Ferns Psilophyta Whisk Ferns Lycophyta Club Mosses Spenophyta Horsetails

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Characteristics : The gametophyte and sporophyte are nutritionally independent of one another The sporophyte - dominant , often branched, long-lived phase. The gametophyte - smaller and either photosynthetic or saprophytic. Because the flagellated sperm need water to swim to the egg (like bryophyte sperm), the gametophyte is restricted in distribution by habitat. The plants are oogamous . Eggs are produced in archegonia, one per archegonium ; sperm in antheridia, many per antheridium. Haploid spores are produced by meiosis in sporangia. The sporangia develop on specialized leaves called sporophylls . Some members of the group have strobili (singular strobilus), cones in which the sporophylls are clustered. A cell plate separates the new daughter nuclei during cell division Cell walls are cutinized (unlike the bryophytes in which a cuticle is lacking ). Seedless Vascular Plants: Pterophyta The spores germinate -a fern gametophyte ( small , photosynthetic prothallus ) attached to the land by rhizoids . Prothallus mature - produce antheridia and/or archegonia . Sperm swim,reaches , and fertilizes, an egg within an archegonium . The zygote grows into an embryo within the archegonium , and then develops into an independently growing sporophyte . A fern sporophyte - horizontal stem (r hizome) ; roots ; erect leaves ( fronds) . At maturity sporangia(stalk and capsule ) develop on the fronds (often in clusters sori ) Each sorus may be covered by indusium . Spores are fomred by Meiosis of cells within the sporangia . Sporangia mature - indusium shrivels and expose them, the wall of each sporangium capsule opens, spores are released Life cycle of Fern

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Seedless Vascular Plants: Psilophyta . Group consisting of two extant genera , Psilotum and Tmesipteris , in one family, Psilotaceae . These plants are primitive in structure: Psilotum lacks both roots and leaves; their stem is an underground rhizomes that fork evenly with enation The rhizomes are infected with mycorrhizae These ferns have a central vascular cylinder composed of xylem and phloem . Psilotum has massive sporangia at axillary positions on the branches. They produce one size of spore ( homosporous ). Spores germinates and forms gametophyte. The gametophyte forms mycorrhizal associations with fungi for nutrition and develops archegonia and antheridia After fertilization a diploid zygote forms and eventually develops into a sporophyte plant.

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Seedless Vascular Plants: Lycophyta ( Club Mosses) Characteristics: Ground Pines, Spike Mosses, and Quillworts (club mosses). Only two living representatives of two major genera ( Lycopodium Selaginella ) Sporophytes have microphylls ; Have true roots and stems . Selaginella – (Spike Mosses) Especially abundant in tropics. Branch more freely than ground pines. Leaves have a ligule on upper surface. Produce two different kinds of spores and gametophytes ( heterospory ). Lycopodium – (Ground Pines) Often grow on forest floors. Resemble little Christmas trees Stems are simple or branched. Develop from branching rhizomes.

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Seedless Vascular Plants: Spenophyta Characteristics: Branches , when present, are normally in whorls at regular intervals along the jointed stems Tiny microphylls in whorls at the nodes. Leaves fused forming a collar. Stems are distinctly ribbed and have obvious nodes and internodes. Significant silica deposits accumulate on the inner walls of the stem’s epidermal cells

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Seedless Vascular Plants Sr. No. Characteristic Pterophyta Lycophyta Sphenophyta Psilotophyta 1. Common members T ree ferns, climbing ferns, Polypodium , maidenhair, fern , bracken, Azolla , Marselia Club mosses, Lycopodium,Selaginella quillworts, Isoetes Equisetum, scouring rushes Whisk ferns, Psilotum , Tmesipteris 2. Spore type Water ferns heterosporous ; all others homosporous Selaginella , Isoetes heterosporous ; Lycopodium homosporous Homosporous ; some fossil members heterosporous Homosporous 3. Leaves M egaphylls Microphylls Microphylls None 4. Steles F ew protosteles ; mostly siphonosteles (complex modifications) Mostly protosteles Modified siphonostele Protostele

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Sr. No. Characteristic Pterophyta Lycophyta Sphenophyta Psilotophyta 5. Sporangia O n sporophylls ; many clustered in sori On sporophylls On sporangiophores in stroboli Lobed lateral; synangia 6. Body and other features T wo kinds: eusporangiate and leptosporangiate ; leaves develop with circinate vernation; small group of water ferns all derived from a terrestrial ancestor Lycopodium and Selaginella small, creeping plants; Isoetes a small hydroilica ; phyte with sharp pointed linear leaves Joint, ribbed, hollow stems impregnated with small leaves in whorls at the nodes; sporangia on special stems or terminal on vegetative ones Dichotomously branched aerial stem only, no leaves, nor roots; rhizomes with rhizoids anchor the plant; endomycorrhizae present in rhizomes Seedless Vascular Plants

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References http://www.marietta.edu/~biol/introlab/Plant%20Diversity.pdf http://scitec.uwichill.edu.bb/bcs/bl14apl/bryo1.htm http://scidiv.bellevuecollege.edu/rkr/botany110/lectures/bryophytes.html http://www.elizajewett.com/portfolio/marchantia.htm http://www.saburchill.com/ans02/chapters/chap040.html http://www.bio.miami.edu/dana/226/226F09_19.html http://biology.clc.uc.edu/courses/bio106/gymnospr.htm http:// generalhorticulture.tamu.edu/lectsupl/anatomy/anatomy.html#page12 http:// faculty.unlv.edu/landau/gymnosperms.htm http:// biology.clc.uc.edu/courses/bio106/angio.htm