Skip to main content
UploadLanguage (EN)Support
BusinessMobileSocial MediaMarketingTechnologyArt & PhotosCareerDesignEducationPresentations & Public SpeakingGovernment & NonprofitHealthcareInternetLawLeadership & ManagementAutomotiveEngineeringSoftwareRecruiting & HRRetailSalesServicesScienceSmall Business & EntrepreneurshipFoodEnvironmentEconomy & FinanceData & AnalyticsInvestor RelationsSportsSpiritualNews & PoliticsTravelSelf ImprovementReal EstateEntertainment & HumorHealth & MedicineDevices & HardwareLifestyle
Uploaded byCherry
PDF, PPTX8,394 views

Classification gymnosperms.............pdf

The document details the classification of gymnosperms into two classes: Cycadopsida and Coniferopsida, highlighting their distinct characteristics and orders. Cycadopsida includes living and extinct groups with features such as large cones and pinnately compound leaves, while Coniferopsida consists of large branched trees and includes diverse groups like Cordaitales and Ginkgoales. Additionally, it describes Gnetopsida as a group morphologically similar to angiosperms, with unique features like opposite leaves and the absence of resin canals.

Science◦
Download as PDF, PPTX
Classification
• Class 1: Cycadopsida – It includes fossil and living forms – Stem is large and stumpy – Large and pinnately compound leaves – Male cones are large and compact with simple microsporophyll – Female cones are loose or pinnate (leaf-like) – Megasporophyll is simple and the ovules are large – Anatomically the stem is with wide cortex – The wood manoxylic type with large amount of parenchyma
• It consists of four orders – Pteridospermales – Bennettitales – Pentoxylales – Cycadales
• Pteridospermales – Are also called cycadofilicales – They are cycad ferns – All are extinct ferns – They appeared in the Devonian period (The Devonian, part of the Paleozoic era, is otherwise known as the Age of Fishes, as it spawned a remarkable variety of fish) and abundant in the carboniferous period – The morphology and anatomy were similar to that of ferns and gymnosperms – Cones not produced – Ovules are directly borne on the leaf margin – Eg: Lyginopteris
• Bennettitales – Are also calledas Cycadeoidales – It is an extinct group – Appeared in the triassic period (The Mesozoic Era begins with the Triassic Period. This era is popularly known as the “Age of Reptiles” and for good reason: reptiles, and particularly dinosaurs, were the dominant land-dwelling vertebrate animalsat the time) – Completely extinct in the cretaceous period (The Cretaceous is defined as the period between 145.5 and 65.5 million years ago,* the last period of the Mesozoic Era, following the Jurassic and ending with the extinction of the dinosaurs (except birds). – Plant body resembles that of living cycads – Have stout or slender stem – Reproductiveparts were flower-like – Cones bisporangiateor monosporangiate – Eg: Cycadeoidea, Williamsonia
• Pentoxylales – A completely extinct group – Plants were shubby – Stems with five vascular strands – Each vascular strand with own cambial ring and undergo secondary thickening – This group was originally described by Prof. Birbal Sahni – Female inflorescence with many cones – Male structure are developed directly on dwarf shoots – Eg: Pentoxylon, Sahania
• Cycadales – They are the living cycadophyta – Most of them are xerophytic in nature – The plant body is palm like and very slow growing – Stem short, un branched covered with persistent leaf scars – Leaves pinnately compound, arranged as a terminal crown – Leaves show circinate vernation – All cycads are dioecious – Ovules are straight (anatropus) – Eg: Cycas, Zamia, Dioon
• Class II-Coniferopsida – Members are large, profusely branched tree forms – Plants with cone like appearance – Leaves are simple – Anatomically the pith is small – Xylem is dense and massive – The wood is pycnoxylic type – Male and female strobili compact and contain complex sporophylls – It consist of four orders • Cordaitales • Confierales • Taxales • Ginkgoales
• Cordaitales – They are the early conifers – Appeared during the carboniferous period – All are extinct, no living representatives – The plants were small tress with star shaped leaves – The reproductive structures were catkin-like clusters – Eg: Cordaites, Mesoxylon
• Coniferales – Mostly evergreen trees – Coniferales present the largest Gymnosperm order (living form) – Plants possess xerophyte adaptations – Leaves usually needle-like and spirally arranged – Wood with a large number of resin canals – Plants monoecious or dioecious – Pollination by wind – Eg: Pinus
• Ginkgoales – Consist of only one extinct genus with one species- Gingko biloba (maindenhair tree) – Living fossil – The plant is native to China – Leaves are broad, bi-lobed with dichotomous viening
• Taxales – Members of Taxales are evergreen small tress or shrubs – An extensively branched plant – Leaves simple, solitary, flat and distichous – Leaf arrangement is spiral – Secondary wood is picnoxylic – Ovules are surrounded by arils – Eg: Taxus
• Gnetopsida – Shrubs or woody climbers – Morphologically similar to angiosperm – Leaves are opposite – Gnetales are only gymnosperm having wood with vessels – Embryo dicotyledonous – Resin canals are absent – A connecting link between Gymnosperm and angiosperm – Contain only one order: Gnetales – Eg: Gnetum, Ephedra, Welwitschia
Classification gymnosperms.............pdf
Classification gymnosperms.............pdf
Classification gymnosperms.............pdf