Homosporous club moss : Homosporous club moss
Heterosporous club moss : Heterosporous club moss
Slide 3 : Pteridophytes
Base for evolution of Seed Plants
Slide 4 :
Slide 5 : Horsetails Equisetum (Horse Tail or Scouring Rush)
A single genus – Equisetum With jointed, ridged, cylindric stems
They are rich in silica, therefore, called scouring rushes, they were used by native Americans to polish their bows.
They bear homosporous
Strobili
Slide 6 : Their spores have four elaters which absorb water and help in germination.
Gametophytes ["prothallia" ]
Slide 7 : FILICINOPHYTA or POLYPODIOPHYTA
"True" ferns About 12,000 species worldwide.
Number of spores per sporangium are fixed.
Stem and petiole are covered by
ramenta, small brown hairs.
They show circinate ptyxis in their leaves.
Major groups are :
Subclass Ophioglossidae
Subclass Osmundacea
Subclass Polypodiidae
Subclass Marsileidae
Subclass Salviniidae
Slide 8 : Fern Leaves Take Many Forms
Adiantum .. The walking fern : Adiantum .. The walking fern Circinate ptyxis
of Adiantum
Slide 10 : AQUATIC FERNS Sporangia are enclosed in the fruit body SPOROCARP in these aquatic ferns
Azolla and Anabaena : Azolla and Anabaena Heterocyst cell
Slide 12 : The Life Cycle of a Homosporous Fern
Slide 13 : Theophrastus Gave his term
Gymnosperms : Gymnosperms Gymnos sperm.......Naked Seed
(From the Greek: gymnos = naked; sperma = seed)
Coined by Theophrastus in his book
“ Enquiry into Plants”
Goebel called them “Phanerogams without ovary”.
SPECIALIZED ROOTS : SPECIALIZED ROOTS Coralloid
Store blue green algae , Nostoc and Anabaena
for nitrogen fixation.
E.g. Cycas with Anabaena cycadeae
Podocarpus
Ginkgo
Zamia
Mycorhizal
Surrounded by mycorhizae
as they lack root hair in
young stages
E.g. Pinus Pinus roots with mycorrhizae
Gymnosperms : Gymnosperms WOOD is MONOXYLIC in Cycas
WOOD is PYCNOXYLIC in Pinus
STOMATA of GYMNOSPERMS are always sunken
LIFE CYCLE shows dominant SPOROPHYTIC Generation (Diploid) which is INDEPENDENT
GAMETOPHYTIC is HIGHLY REDUCED and DEPENDENT upon SPOROPHYTE
REPRODUCTIVE Organs are aggregated into compact Cones called as strobili except in female Cycas
Cones can never be monoecious or bisexual
Slide 17 : Female foliarMegasporophylls of Cycas
Slide 18 : > year after
pollination Vascular Seed Plants - Gymnosperms
Slide 19 :
Gymnosperms : Gymnosperms Most characteristic regarding development of GYMNOSPERMS is Polyembryony
EMBRYO is Endoscopic
Embryo is developed at the end of long SUSPENSOR which is pushed down into NUCELLUS which is
Haploid tissue
Whole of the Nutritive tissue NUCELLUS is crushed except little conical cap which is called as PERISPERM
Number of Cotyledons are 6 to 15
Therefore Gymnosperm are Polycotyledonary.