Seedless vascular plants Seedless vascular plants Reduction of the gametophyte Monophyletic linage Seedless vascular plants • Phyla or Divisions of seedless vascular plants Running-cedar or Fan Ground-pine – Rhyniophyte (extinct) – Zosterophyllophyte (extinct) – Trimerophyphyte (extinct) – Lycopodiophyta – Pteridophyta ferns Organization of the seedless vascular plant body – Root and shoot systems – Dermal tissue system • dermal • vascular • ground – Vascular tissue system • xylem • Phloem – Ground tissue system – Primary growth – Secondary growth Evoluon of the vascular system • Tracheids (primitive conduction) • Vessel elements (convergent evolution) or stele Protostele: (Primitive) solid cylinder of vascular tissue. Siphonostele: Most common in seedless vascular plants. Central pith surrounded by vascular tissue Eustele: Organized with vascular bundles. Independent evolution from protostele Microphylls: with single strand of vascular ;ssue. Originated as enaons. Megaphylls: with branching veins, associated with siphonosteles, leaf gaps and eusteles. Originated by fusion of branch systems. Reproduction All vascular plants • Oogamous • Alternation of heteromorphic generations (sporophyte dominant) • Homosporous or heterosporous – Homosporous Produce bisexual gametophytes • (A) Antheridia • (B) Archegonia • Not self fertilized Reproduction – Heterosporous • megaspores produced in • microspores produced megasporangia in microsporangia = ♀ gametophyte = ♂ gametophyte (a.k.a. megagametophyte) (a.k.a. microgametophyte) • Unisexual gametophytes • Gametophytes of homosporous plants – photosynthetic • Gametophytes of heterosporous plants – dependent of sporophyte Extinct groups • Leafless dichotomously • Dichotomously branched branched • Stems with terminal sporangia • Vascular tissue similar to hydroids in mosses • Homosporous • Cuticle, epidermis, cortex, stomata and photosynthetic stems • Isomorphic generations • Marshes Minimal differen;aon of Phylum / Division roots/stems Rhyniophyta ! Phylum / Division Zosterophyllophyta and Trimerophyta Zosterophyllophyta Trimerophyta • 370-408 MYA • 395-415 MYA • Laterally borne kidney- • Evolved from Rhyniophyta shaped sporangia • Large vascular strand • Grass-like appearance • Ancestor of pteridophytes and • Ancestor of lycophytes progymnosperms Phylum Lycopodiophyta • 1200 sp. • Trees or herbs with secondary growth • All of them possess microphylls • 400 MYA divergence from – lycophytes – club mosses • tree lycophytes dominant in Carboniferous – Euphyllophytes – ferns, horsetails, seed plants Spores with high oil content. Family Lycopodiaceae strobili Cone-like • 15 genera, 1200 sp. • Club moss (Lycopodium sp.) • Arctic to tropics, evergreen • Rhizome with roots and stems • Spiral microphylls • Sporangia on sporophyll • Homosporous • Some sporophylls non-photosynthetic • Bisexual gametes • Cross-fertilize – 6 - 15 yrs for mature archegonia/ antheridia • Biflagellate sperm • Independent sporophyte Family Selaginellaceae • 1 genus, 750 sp. • Tropics to deserts • Selaginella – resurrection plant • Ligule = small, scale-like outgrowth at the base of sporophylls Protostele Trabeculae Family Selaginellaceae • Heterosporous – Megasporangia – Microsporangia contained on single strobili • Biflagellate sperm • Suspensor connection between the embryo and the nutrient-rich tissue in the female gametophyte • Sporophyte parasite of gametophyte Family Isotaceae • 1 genus Isoetes (quillwort) • Sporophyte body – underground stem and roots – microphllys • Heterosporous • Cambium produces 2º tissues ü sieve elements ü tracheids ü parenchyma • Sediment as source of Carbon from sediment – Lack stomata – Thick cuticle, – Minimal gas exchange with atmosphere – CAM Phylum Pterophyta • 11,000 sp. • Some epiphytic • Now includes Sphenophyta (horsetails) • Homosporous or heterosporous Phylum Pterophyta • 2 types of sporangia – eusporangia = multiple initials or parent cells • inner layer = irregular mass, gives rise to spore mother cell • outer layer = sporangium wall Phylum Pterophyta – leptosporangia = one superficial initial • stalked sporangium • capsule with nutritive tissue (tapetum) • tapetum è annulus that contracts to catapult spores • inner tissue becomes spore mother cells Phylum Pterophyta. Equisetales One genus: Equisetum (horsetails) Homosporus Spores with elaters • Shoot with terminal strobilus. • Whorls of scale-like leaves • Photosynthetic shoot • Low content • Nodes and internodes of chlorophylls or no Perennial rhizomes chlorophylls .