VASCULAR PLANTS WITHOUT SEEDS

• VASCULAR PLANTS WITHOUT SEEDS

  • reproduce by forming spores rather than seeds
  • have specialized vascular tissue (xylem and phloem)
  • can grow larger than bryophytes
  • have leaves that can perform photosynthesis

  ⚬ microphyll - leaf found in lycophytes (contains one vascular strand)

  ⚬ megaphyll - leaf found in all plants except lycophytes (contains multiple vascular strands)
• PTERIDOPHYTA

  • Bracken (Pteridium aquilinum): most common fern species; a rugged, coarse, “weedy” plant that grows well on poor soil and is uncommon in the moist habitats favored by other ferns
  • WHISK FERNS
  • HORSE TAILS
• PTERIDOPHYTA

  • ferns reproduce by spores produced in sporangia; undergoes an alternation of generations between dominant sporophytes and a gametophyte (prothallus)
  • terrestrial, although few have adapted to aquatic habitats
  • found in tropical rain forests perching high in tree branches; temperate regions, in swamps and marshes, moist woodlands and stream banks; some species grow in fields, rocky crevices, on cliffs or mountains, or even deserts
• WHISK FERNS

  • reduced ferns
  • live mainly in tropics and subtropics
  • relatively simple in structure and lack true roots and leaves but have vascularized stems
  • aerial stem resembles to a whisk broom, hence the name rhizome with its attached rhizoids: absorbs water and dissolves minerals
  • aerial stem are green and photosynthetic
  • have dichotomous branching (when the stem forks or branches, it always divides into two equal halves
  • e.g. Psilotum nudum
• HORSE TAILS

  • few surviving, about 15 spp in the single genus Equisetum, grow mostly in wet marshy habitats and are small distinctive plants
  • found in every continent except Australia
  • have true roots, stems (both rhizomes and erect aerial stems), and small leaves
  • contains silica at jointed stem which gives it a gritty texture
  • small leaves (interpreted as reduced megaphylls) are fused in whorls at each node
  • have green stem (main organ for photosynthesis)
• HORSE TAILS

  ⚬ strobilus – terminal and cone-like found in the reproductive branch of horse tails

  ⚬ elaters – appendages in horsetail spores that uncoil as the spores dry out

  ⚬ sporophyte (conspicuous plant; gametophyte) minute, lobed thallus ranging in width from a

  size of a pinhead to about 1 cm across. *both are photosynthetic and nutritionally independent upon maturity requires water as a medium for flagellated sperm cells to swim
• HORSE TAILS

  • also called “scouring rushes” and were used to scrub out pots and pans along stream banks
  • aerial stems of horsetails are either vegetative (sterile) or reproductive (fertile)
• SPIKE MOSSES, QUILLWORTS, AND SOME FERNS ARE

  • Homospory – production of one type of n spore that give rise to bisexual gametophytes
  • Heterospory – production of two type of n spores, microspores, and megaspores
  • Microspore – the n spore in heterosporous plants that gives rise to a male gametophyte
  • Megaspore – The n spore in heterosporous plants that gives rise to female gametophyte
• LYCOPODIA

  • some are heterosporous
  • large treelike plants, like ancient horsetails were major contributors to our present day coal deposits
  • characterized by leaves that are microphylls (for both living and extinct lycophytes)
  • CLUB MOSSES
  • SPIKE MOSSES
  • QUILLWORTS (Isoetes)
• CLUB MOSSES

  • Evergreen are often fashioned into Christmas wreaths
  • life cycle is similar to that of ferns – both sporophyte and gametophyte are
  • independent plants at maturity
  • like whisk ferns they form symbiotic relationship with mycorrhizal fungi that provide them nourishment)
  • requires water as a medium in which flagellated sperms swim to the egg in the
  • archegonium
• SPIKE MOSSES

  • long creeping rhizomes and typically branch dichotomously
  • roots are produced at branching along the length of the stems (branch dichotomously)
• SPIKE MOSSES

  • S. lepidophylla -resurrected plant that are native to prairies and deserts of Texas and Mexico

  ⚬ when conditions are dry, this species curls up into a brown ball and becomes dormant, but when

  moisture is again available, it is “resurrected” – that is, i t expands and becomes green and

  photosynthetic
• SPIKE MOSSES

  • overlapping, scalelike leaves, which are microphylls, have single unbranched vein; leaves are arranged in four vertical rows in many spp.

  ⚬ ligule: inconspicuous outgrowth on the upper surface near the base of the leaf

  ⚬ selaginella – living spike mosses; common in shady, moist tropics and subtropics, but some grow in temperate climates
• QUILLWORTS (Isoetes)

  • perennial aquatic or semiaquatic herbs that ar widely distributed in temperate, freshwater habitats
  • have a CORM with cylindrical, quill-like leaves (microphylls) grow in a clump from the base
  • roots that arise from the corm divide dichotomously
  • aerial stems are absent
• QUILLWORTS (Isoetes)

  • spore-bearing vascular plants

  ⚬ Megasporangia- produce few large megaspores; located at the bases of the outer leaves

  ⚬ Microsporangia – produce many smaller microspores that are at the bases of inner leaves requires water as a medium