SYSTEMATICS (FINAL LEC QUIZ)

• Ten Phyla of Extant Plants

  • Hepatophyta (Liverworts)
  • Anthocerophyta (Hornworts)
  • Bryophyta (Mosses)
  • Lycophyta (Lycophytes)
  • Pterophyta (Pterophytes)
  • Ginkgophyta (Ginkgo)
  • Cycadophyta (Cycads)
  • Gnetophyta (Gnetophytes)
  • Coniferophyta (Conifers)
  • Anthophyta (Flowering plants)
• Bryophytes


  Nonvascular plants
• Bryophytes are represented today by three phyla of small herbaceous (nonwoody) plants
• Bryophyte phyla


  • Hepatophyta (Liverworts)
  • Anthocerophyta (Hornworts)
  • Bryophyta (Mosses)
• Bryophyte gametophytes


  • Produce flagellated sperm in antheridia
  • Produce ova in archegonia
  • Generally form ground-hugging carpets and are at most only a few cells thick
• Bryophyte sporophytes


  • Grow out of archegonia
  • Are the smallest and simplest of all plant groups
  • Have conducting tissues in the center of their "stems" and may branch
  • Consist of a foot, a seta, and a sporangium
• The foot absorbs nutrients from the gametophyte, the seta conducts these materials to the sporangium or capsule, which uses them to produce spores by meiosis
• When the capsule is mature, the spores are released
• Hornwort and moss sporophytes have stomata
• Liverworts


  Phylum Hepatophyta, "thalloid" and "leafy" types
• Hornworts


  Phylum Anthocerophyta
• Mosses


  Phylum Bryophyta, including Polytrichum commune (hairy-cap moss)
• Sphagnum, or "peat moss", forms extensive deposits of partially decayed organic material known as peat and plays an important role in the Earth's carbon cycle
• The acidic, oxygen-poor conditions produced by Sphagnum can preserve human or other animal bodies for thousands of years
• Bryophytes and bryophyte-like plants were the prevalent vegetation during the first 100 million years of plant evolution
• Vascular plants began to evolve during the Carboniferous period
• Vascular plants


  • Have independent, branching sporophytes
  • Have two types of vascular tissue: xylem (conducts water and minerals) and phloem (distributes organic products)
• Microphylls


  Leaves with a single, unbranched vascular tissue
• Megaphylls


  Leaves with a highly branched vascular system
• Sporophylls are modified leaves with sporangia
• Most seedless vascular plants are homosporous, producing one type of spore that develops into a bisexual gametophyte
• Some seedless vascular plants and all seed plants are heterosporous, having two types of spores that give rise to male and female gametophytes
• Phyla of seedless vascular plants

  • Lycophyta (Club Mosses, Spike Mosses, and Quillworts)
  • Monilophyta (Ferns, Whisk Ferns and their relatives)
• Lycophytes


  Phylum Lycophyta, including club mosses, spike mosses, and quillworts
• Monilophytes


  Phylum Monilophyta, including ferns, whisk ferns and their relatives
• Heterosporous


  Having two types of spores that give rise to male and female gametophytes
• Seedless vascular plants form two phyla
• Phylum Lycophyta


  • Club Mosses
  • Spike Mosses
  • Quillworts
• Phylum Monilophyta


  • Ferns
  • Whisk Ferns and their relatives
  • Horsetails
• Lycophytes


  • Are small herbaceous plants
  • Some live below ground, nurtured by symbiotic fungi
  • Sporophytes have upright stems with many small leaves, as well as ground hugging stems that produce branching roots
  • Gametophytes live above ground and are photosynthetic
• Ferns


  • Are the most diverse seedless vascular plants
  • Almost all species are homosporous
  • Have megaphylls, the sporophytes typically have horizontal stems that give rise to large leaves called fronds, often divided into leaflets
• Horsetails


  • Today, only 15 species survive as a single, widely distributed genus, Equisetum, found in marshy places and along streams
  • Are homosporous, with cones releasing spores that typically give rise to bisexual gametophytes
• Whisk Ferns and Relatives

  • Psilotum (whisk ferns) and a closely related genus, Tmesipteris, are tropical epiphytes
  • They are lacking true roots, are called "living fossils"
  • Both are homosporous but the sporophytes of Psilotum have dichotomously branching stems
• The ancestors of modern lycophytes, horsetails, and ferns grew to great heights during the Carboniferous, forming the first forests
• The growth of these early forests may have helped produce the major global cooling that characterized the end of the Carboniferous period
• Decayed and eventually became coal
• Seeds changed the course of plant evolution, enabling their bearers to become the dominant producers in most terrestrial ecosystems
• Homospory


  Plants have two further variations on their life cycles. Plants that produce bisexual gametophytes have those gametophytes germinate from isospores (iso=same) that are about all the same size.
• Heterospory


  Plants that produce separate male and female gametophytes have those gametophytes germinate from (or within in the case of the more advanced plants) spores of different sizes.
• Seed plants evolved from plants that had heterospory