HORNWORTS
– 100 SPECIESNAMED FOR IT’S HORNLIKE SPOROPHYTIC
GENERATION
GAMETOPHYTIC GENERATION DOMINANT
SPOROPHYTE GENERATION IS DEPENDENT
ON THE GAMETOPHYTE GENERATIONDIVISION ANTHOCEROTOPHYTA (OR ANTHOCEROPHYTA)
HABITAT: TROPICAL FORESTS, ALONG STREAM SIDES, IN DISTURBED FIELDS, USUALLY ON SOIL BUT CAN BE ON TREE TRUNKS
SIZE AND APPEARANCE: SMALL, GREASY BLUE-GREEN
MORPHOLOGY OF GAMETOPHYTE
GAMETOPHYTE THALLOSE AND GREASY BLUE-GREEN IN COLOR. THE THALLUS IS ORBICULAR OR RIBBON-LIKE AND HAS A MIDLINE
CELLS HAVE A SINGLE LARGE CHLOROPLAST
COMPLETELY ENVELOPING THE NUCLEUS
SPACES BETWEEN CELLS ARE FILLED WITH MUCILAGE RATHER THAN AIR MAKING MUCILAGENOUS CANALS
THE CYANOBACTERIA, NOSTOC, LIVES IN THESE CANALS
b. HORNWORT PROVIDES CARBOHYDRATES TO THE NOSTOC
THIS IS A SYMBIOTIC RELATIONSHIP THAT CAN BE DESCRIBED AS MUTUALISM
THE GAMETANGIA (GAMETE PRODUCING STRUCTURES) ARE PRODUCED ALONG THE THALLUS MIDLINE
a. ARCHEGONIA ARE SUNKEN INTO THE
SURFACE OF THEb. ANTHERIDIA ARE LOCATED IN CHAMBERS BENEATH THE
SURFACE (ENDOGENOUS)
RHIZOIDS ANCHOR THE GAMETOPHYE TO ITS SUBSTRATE
MORPHOLOGY OF THE SPOROPHYTE
THE SPOROPHYTE IS COMPOSED OF A BULBOUS FOOT AND AN ELONGATED CYLINDRICAL
SPORE-BEARING REGION.
THE FOOT IS BURIED IN THE GAMETOPHYTE
THE GROWTH OF THE SPORE BEARING REGION IS INDETERMINANT. IT GROWS FROM A MERISTEM JUST ABOVE THE FOOT.
SPORE MATURATION OCCURS FROM THE BASE UPWARD
STOMATES ARE FOUND IN THE EPIDERMAL LAYER OF THE SPOROPHYTE AND ARE THE ONLY EPIDERMAL CELLS TO HAVE CHLOROPLASTS.
A PHOTOSYNTHETIC LAYER IS LOCATED BENEATH THE EPIDERMIS
THE SPORE PRODUCING TISSUE LIES BENEATH THE PHOTOSYNTHETIC LAYER
a. SPORES ARE ARRANGED AS TETRADS IN THE
SPOROPHYTE
b. SPORES ARE SEPARATED AND DISPERSED
INDIVIDUALLY
SPORE DISPERSAL
THE SPOROPHYTE SPLITS ALONG TWO LONGITUDINAL LINES, STARTING NEAR THE TIP
PSEUDOELATORS HELP DISPERSE THE SPORES
EACH SPORE GIVES RISE TO ONE GAMETOPHYTE