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Nonvascular Plants: Mosses, Liverworts, and Hornworts (Concepts (green…

- - - - sporophytes are usually small and depend on gametophyte for nutrients so they never stray far from them
      - gametophyte, haploid phase, photosynthetic, perennial and collecting nutrients is what you commonly see
      - sporophytes will never be seen independent of gametophytes and never branch or have leaves
  - - - have multicellular sporangia and gametangia, reproductive cells are always surrounded by one or several layers of sterile cells :red_flag:
      - bodies made of true parenchyma derived from three-dimensional growth from apical meristems :star:
      - nonvascular plants are almost exclusively terrestrial and have a cuticle over much of their bodies, many have stomata
- - - - most liverwort sporophytes have a foot, seta and calyptra covered sporangium but seta very delicate :star:
      - liverwort sporangium lacks a columella, the central mass of sterile cells found in mosses
        
        within the sporangium, some cells do not undergo meiosis but rather differentiate into elaters-single elongate cells with spring shaped walls
      - very little variability exists in the sporophytes of most liverworts and their basic morphology is like that of mosses :check:
      - simple sporophytes can be produced containing no foot or seta, instead inner cells of the mass undergo meiosis and produce spores :warning:
    - - thallose liverworts :star:
        
        thallus means a body without roots, stems and leaves. Bodies tend to be thicker and stratified :check:
        
        cells are loosely arranged as an aerenchyma with large air chambers that open to exterior by means of air pores :red_flag:
        
        is less like a moss as they are not leafy but flat and ribbon like
        
        some species can be simple with a small ribbon shape and only one cell think, with simple rhizoids and no air chambers
        
        can be bisexual or unisexual depending on the species
        
        male gametophores of Marchantia produce umbrella-shaped outgrowth called an anteridiophore :check:
        
        has a stalk several mm tall and dozens of antheridia grow form its upper surface surrounded by rim of sterile cells
        
        Archegoniophore are also stalked, but apex is a set or radiating fingers that project outward and droop downward, underside contains numerous archegonia
      - in both, gametophyte phase is initiated when spores germinate and establish small, temporary protonematal phase
      - leafy liverworts :check:
        
        resemble mosses with thin leaves on sleder stems however has two rounded lobes and no midrib or conducting tissue :red_flag:
        
        leaves have three clearly defined rows, two being larger than the third
        
        prostrate causes underside to be reduced, may even be completely suppress or replaced by rhizoids
        
        gametophore stem grows by an apical cell with 3-5 sides, one uppermost and others embedded :black_flag:
        
        stem tissue is just simple parenchyma, no thick walls. have ssome cells that contain characteristic oil bodies :star:
- - - - this develops into a small bulbous tissue called the foot :star:
      - the upper cell that grows by cell division and expansion into a simple apical sporangium called the capsule :star:
      - between the foot and capsule is a narrow stalk, the seta, all moss sporophytes have this basic simple structure. never branched :black_flag:
    - - cell breakage is elaborate and precise, resulting in one or two rows of beautiful complex teeth called peristome teeth
      - apex of the sporangium in many species in many species is covered by a calyptra, layer of cells derived from neck of archegonium
      - contains a true epidermis with stomata
      - virtually all mosses are homosporous, all spores are the same size and appear to be identical
      - apex of the sporangium differentiates as a caplike lid called the operculum, separates from the rest of sporangium as cells torn :check:
    - - on vascular plants are small and offer little nutrients and protection fro embryonic sporophytes
      - fro flowering plans, typically have only six cells other than the egg
      - all nutrition for the zygote is supplied by the grandparent generation
      - moss gametophytes are both large and photosynthetic and support sporophyte throughout life. Never independent :check:
  - - - tolerant of desiccation, these can be resistant to high and low temperatures and intense UV light :warning:
      - can grow on hard impervious surfaces because they have no roots to penetrate substrate
      - grow permanently in moist climates
  - - - Water transport
        
        along with hydroids, species will have leptoids, that resemble sieve tubes :check:
        
        elongated cells, prominent interconnections with adjacent cells, lack nuclei at maturity and retain cytoplasm
        
        adjacent parenchyma cells are unusually cytoplasmic and rich in enzymes just as companion cells.
        
        majority of mosses lack hydroids and leptoids, rely on capillary action along leave to move water :star:
        
        at base of stem are rhizoids, small, multicellular trichome-like structures that penetrate the surface of the substrate :star:
        
        rhizoids only anchor stem, do not absorb either water or minerals. Lack chloroplasts and have reddish walls
        
        leaves and stems small enough that they form narrow spaces that act as capillary channels and transport water
        
        in some mosses, innermost cortex is composed of cells called hydroids that conduct water and dissolved minerals :star:
        
        they are elongated cells that lose cytoplasm when mature, end walls partially digested, and aligned with others above and below
      - Development
        
        eventually nodules of small sytoplasmic cells form on the protonema which is an organized apical cell :check:
        
        protonoma are perennial and can grow extensively, producing many buds
        
        filamentous cells usually break when mosses are collected and appear to be independent of plants when they are not
        
        growth of the gameophore begins when a spore germinates and sends out a long, slender chlorophyllous cell :star:
        
        cell will undergo mitosis and produce a branched system of similar cells. An entire network is called a protonema
        
        protonema superficially resembles a filamentous green alga but can be distinguished by numerous chloroplasts in each cell
      - Morphology
        
        all most leaves have stems have leaves but because they are apart of gametophyte, they are not homologous :star:
        
        moss gametophytes grow from apical meristem that contains a prominent apical cell :check:
        
        cuticle only occurs on the upper surface of most moss leaves, underside uncutinized and capable of absorbing water
        
        lack of cuticle means little protection against desiccation, when microhabitat dries, leaves dries
        
        leaves of moss are almost always one cell thick except in midrib and along margin
        
        no stomata occurs on leaves
        
        the leafy stem known as gametophores, many mosses grow together :check:
        
        cooler and wetter environments allow openness and looseness
        
        Moss stems are always slender and have little tissue differentiation. :star:
        
        stem tissues all called cortex, may be uniform in all parts or the outer cells may be slightly narrower with thicker walls :check:
        
        inner cells are larger, more parenchymatous and chlorophyllous
        
        surface layer is at most, only slightly different from the underlying layers and not called epidermis :black_flag:
        
        some species of moss, stem have hairs but stomata do not occur
      - Reproduction
        
        sperm is produced in microgametangia called antheridia :star:
        
        consist of a short stalk, outermost layer of sterile cells and an inner mass of cells that differentiate into sperm cells
        
        eggs occur in the megagametangia called archegonia, shaped like vase with long neck and is hollow at maturity :check:
        
        gametophore at some point produces gametangia
        
        both atheridia and archegonia occur on the same gametophore in bisexual plants
        
        when sperm cells mature, antheridium breaks open and liberates sperm cells either by contracting sterile outer cells or accumulating liquid and pushing sperm out
- - - - mucilage chambers fromed when cells break down and contents altered chemically into mucilage :warning:
      - form symbiosis with cyanobacteria for benefit of nitrogen compounds
    - - as sperm cells mature, sterile outer cells of antheridia transform their chloroplasts into chromoplasts :large_orange_diamond:
      - archehonia formed from superficial cells, do not completely surround the egg as do the archehonia of other embryophytes
      - antheridial initials are not surface cells on hornwort gametopyte, instead have mucilage chamber grow into antheridia
  - - - characteristic of many algae and represent condition of the ancestors of all embryophytes