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
Organization of the seedless vascular plant body
– Dermal tissue system • dermal • vascular • ground
– Vascular tissue system • xylem • Phloem
– Ground tissue system
– Primary growth – Secondary growth Evolu on 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 ena ons.
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 a on 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