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cycas.pptx

This document provides information about the plant Cycas, including its systematic position as a gymnosperm in the division Cycadophyta. It describes key aspects of the Cycas plant body such as its short, tuberous stem covered in tough leaf bases that bears a crown of large fern-like leaves. The document outlines the structure and development of Cycas female cones and ovules, which have an erect structure with a micropyle opening and integument layer that becomes stony during seed formation. References on gymnosperms and the genus Cycas are also provided.

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Course Code: Bot-301 Course Title: Diversity of Plants Credit Hours: 3(2-1) Dr. Riffat Nasim Fatima and Dr. Sana Tehseen Assistant professor Department of Botany GCWUF
Cycas is commonly found in tropical and subtropical regions of the world Cycas revoluta (sago palm) is most common and widely studied species in the sub-continent It is cultivated for yield of starch-rich sago used as food Cycas circinalis is cultivated as ornamental for its large attractive palm-like leaves
Systematic Position Gymnospermae Division: Cycadophyta Class: Cycadopsida Order: Cycadales Family: Cycadaceae Genus: Cycas (Greek word kykos means a palm/cocopalm)
Plant Body Cycas plant body is a heterosporous sporophyte Cycas plant shows a short, tuberous, unbranched stem which bears a crown of large fern-like leaves Stem is covered with tough leaf bases In some species large adventitious buds called bulbils develop on the basal part of the stem These bulbils contain reserve food material and help in vegetative propagation
Leave of caycas are pinnately compound and exhibit circinate vernation Shoot apex is protected by a rosette of brown scale leaves Plants grow very slowly adding a new crow of leaves every 2 or 3 years, alternating with a crown of scale leaves Each crown remain on the stem for many years
Root of cycas plant is of two types; Normal and Coralloid Normal roots: Normal tap roots grow from radical deep inside the soil giving out lateral branches Some of the lateral roots grow apogeotropically towards the surface of soil and branch dichotomously These roots are short, thick and swollen at the tips
Much branched mass appears like a coral on the soil surface hence called as coralloid roots Do not bear root caps Cluster has lenticel like apertures Become infested with blue green algae to fin atmospheric N2 In this way a symbiotic relationship is established
Female Cone
Structure of Ovule Ovule is erect and has an opening called as micropyle The part opposite to micropyle is called as chalaza Massive nucellus is surrounded by a single integument Integument is differentiated into outer, inner and middle layer (thick that become stony during seed formation) The nucellus is equivalent to megasporangium and consists of thin walled parenchyma having dense cytoplasm Nucellus grows into a beak called nucellor beak The upper part of beak form pollen chamber and pollens are lodged into it after pollination
References https://study.com/academy/lesson/gymnosper ms-characteristics-definition-types.html https://www.slideshare.net/SyedaFari2/cycas https://www.slideshare.net/MohdTariq25/gym nosperm-characteristics https://slideplayer.com/slide/14446521/ https://www.slideserve.com/varsha/cycas- structure-reproduction-life-cycle https://www.easybiologyclass.com/general- characters-of-gymnosperms-lecture-notes- with-ppt/
cycas.pptx