5. Seedless Vascular Plants- Ferns And Whisk Ferns.pdf

Seedless Vascular Plants Pteridophytes · Vascular tissue present in extant only in the...

Seedless Vascular Plants Pteridophytes · Vascular tissue present in extant only in the sporophyte stage, groups never the in gametophyte stage e. · A dominant sporophyte stage (with Vascular tissue) means that ferns fossilized well and had good structure e. The function of the tall sporophyte to produce · is spores growing was advantageous : Presence of Vascular tissue was advantageous. Introduction : · Extinct phylum Rhyniophyta first vascular plants with substantial fossil. record · Genus Cooksonia best known of these fossils · Rhyniophyta : first truly sucessful land plants fully liberated from abundant surface water. Developed effective · an vascular tissue system. True didn't time with suddenly gradually · stems organs appear over first. appearing · Seedless vascular plants characterised by the presence of vascular tissue + absence of seeds. · Vascular tissue : columns of elongate , specialised cells that form a network through -  out the plant from roots to leaves. Xylem transports water · : and salts from roots to of rest plant · Phloem : transports glucose + hormones from source (leaves) to where needed. · Seeds are a much more recent adaptatio n · Vascular plant also cuticle possess a + Stomata. · New characters that developed in seedless vascular plants Dominant sporophyte generation Vascular tissue True organs /roots , stems + leaves · What is the origin of leaves ? Microphylls + Megaphylls 2 types of leaves in seedless vascular plants Megaphylls typical leaves · are Defined through their evolutionary origin as systems of branching stems. · Branching patterns gradually altered through evolutionary tim e. 1. Orientation of smaller stems into the same flat plane ("planation").. 2 Differential growth rates of some stems ("overtopping"). 3. Parenchyma tissue filled in gaps between stems ("webbing").  Microphylls considered to have entirely · are an different from of the origin develop outgrowths main stem axis. Easy to tell the difference between · Mega-and microphylls : have branched leaf megaphylls multiple , Veins have single unbranched leaf microphylls a , vein. Seedless vascular plant diversity :.. Pterophyta (ferns + whisk ferns ( 2. Equisetophyta (horsetails) (club mosses 3. Lycophyta Sporophyte dominant · generation is in all vascular plants. Primary function of sporophytes · produce spores via meiosis in sporangia. · Exclusive presence of vascular tissue in extant sporophytes means sporo- phytes larger/taller than corresponding gametophytes. More effective dispersal of wind vector · spores using as a. Substantial the bear their diversity in that plants · vascular way sporangia. 4 Major strategies in the seedless vascular plants · : · Seed + non-seed plants are not separable on grounds of presence or absence of cones. · Present in Lycophyta and Equise- absent tophyta ; Pterophyta. · Cones one of the most B events in the reproductive organiz of sation plants precursor of the flower. · Flowering plants (most diverse + complex group) sporangia confined to flowers strobili. heavily modified 1 Phylum Pterophyta (terns Largest seedless plant with · vascular ca 12000 group. extant species. · Together with horsetails/whisk ferns considered to , be the to the sister group seed plants. · True ferns evolved more than 350 m a in the y... Devonian Period. Today ferns flourish terrestrial · in ecosystems across the globe (75 % in tropics). · Dominant sporophyte varies in 24 m (tree ferns). · Always bigger than the gametophyte : gametophyte seldom