VASCULAR PLANTS WITH SEEDS

• Gymnosperms (non-flowering plants)

  • Most are evergreens meaning they don’t lose their leaves seasonally
  • are also perennials (EVERGREEN), growing back every year with no need for replanting
  • Their reproductive system of gymnosperm plants is located in the cones

  ⚬ female cones grow in the upper branches of the tree and male cones grown on the lower branches
• Gymnosperms (non-flowering plants)

  • comes from the Greek words gymnos meaning “naked” and sperm which means “seed”
  • have needle-like or scale-like leaves and no flowers
  • They have woods that are softer than that of angiosperms and is used to make paper and lumber
• CONIFEROPHYTA (Conifers)

  • similar in production of secondary cambium and pattern of seed development with Cycadophyta and Ginkgophyta but are not closely related phylogenetically to each other
  • the dominant phylum of gymnosperms, with the most variety of species
  • typically tall trees that usually bear scale-like or needle-like leaves
  • water evaporation from leaves is reduced by their thin shape and the thick cuticle making the now slides easily off needle-shaped leaves, keeping the load light and decreasing breaking of branches
• CONIFEROPHYTA (Conifers)

  • adaptations to cold and dry weather explain the predominance of conifers at high altitudes and in cold climates
  • coniferous trees are harvested for paper pulp and timber.
  • conifer woods are more primitive than the wood of angiosperms; it contains tracheids, but no vessel elements, and is, therefore, referred to as “soft wood”
  • some species are deciduous (lose their leaves in fall)
  • examples: pines, cedars, spruces, sequoias, firs, yews
• CYCADOPHYTA (Cycads)

  • cycads face possible extinction but several species are protected through international conventions
  • often used as ornamental plants in gardens in the tropics and subtropics because of their attractive shape
• CYCADOPHYTA (Cycads)

  • similar in production of secondary cambium and pattern of seed development with Coniferophyta and Ginkgophyta but are not closely related phylogenetically to each other
  • cycads thrive in mild climates
  • often mistaken for palms because of the shape of their large, compound leaves
  • they bear large cones and may be pollinated by beetles rather than wind, which is unusual for a gymnosperm
  • dominates the landscape during the age of dinosaurs in the Mesozoic, but only a hundred or so species persisted to modern times
• GINKGOPHYTA (Ginkgophytes)

  • cultivated by Chinese Buddhist monks in monasteries for centuries, which ensured its preservation
  • mostly planted in public spaces because it is unusually resistant to pollution
  • male and female organs are produced on separate plants

   typically, gardeners plant only male trees because the seeds produced by the female plant have

  an off-putting smell of rancid butter
• GINKGOPHYTA (Ginkgophytes)

  • similar in production of secondary cambium and pattern of seed development with Cycadophyta and Coniferophyta but are not closely related phylogenetically to each other
  • Ginkgo biloba is the single surviving species of the gingkophytes group
  • has fan-shaped leaves, unique among seed plants because they feature a dichotomous venation pattern, turn yellow in autumn and fall from the tree
• GNETOPHYTA (Gnetophytes)

  • like angiosperms, but unlike other gymnosperms, all gnetophytes possess vessel elements in their xylem
  • examples:

   Welwitschia

   Ephedra - its small, scale-like leaves are the source of the compound ephedrine, which is used in

  medicine as a potent decongestant but use is restricted to prescription drugs because it has similar chemical structure and neurological effects to amphetamines
• GNETOPHYTA (Gnetophytes)

  • the closest relative to modern angiosperms
  • have broad leaves like angiosperms
  • gnetophytes are vines or small shrubs in tropical and subtropical zones
  • Ephedra occurs in dry areas of the West Coast of the United States and MexicoEphedra’s small, scale-like leaves are the source of the compound ephedrine, which is used in medicine as a potent decongestant. Because ephedrine is similar to amphetamines, both in chemical structure and neurological effects, its use is restricted to prescription drugs.