DIVISION PTERIDOPHYTA: FERNS

12,000 LIVING SPECIES (LARGEST

DIVISION OF SEEDLESS VASCULAR PLANTS

FOUND IN THE TROPICS, TEMPERATE FORESTS, EVEN DESERTS

FERN FRONDS (LEAVES) CAN BE AS BIG AS A TWO CAR GARAGE, OR AS SMALL AS A GRAIN OF RICE

CHARACTERISTICS

1. LEAVES (FRONDS) GROW FROM A FLESHY RHIZOME
       a. YOUNG LEAVES ARE COILED INTO FIDDLEHEADS
      DUE TO CIRCINNATE VERNATION

CIRCINNATE VERNATION IS CAUSED BY ONE LEAF SURFACE
GROWING FASTER THAN THE OTHER

   b. USUALLY FERTILE

SPORANGIA CLUSTER INTO A SORUS ON THE UNDERSIDE OF
THE FROND (SORI, pl.)

SORUS COVERED BY AN OUTGROWTH OF TISSUE FROM THE
LEAF CALLED AN INDUSIUM

TWO TYPES OF SPORANGIUM DEVELOPMENT

- EUSPORANGIATE - SPORANGIA ARISE FROM SEVERAL CELLS ON THE UNDER-SURFACE OF THE FROND

- LEPTOSPORANGIATE -

SPORANGIA ARISE FROM A SINGLE SURFACE CELL

LEPTOSPORANGIATE IS THE MOST COMMON CONDITION

   c. HOMOSPOROUS - ALL SPORES APPEAR IDENTICAL
              1. DEVELOPE INTO A BISEXUAL GAMETOPHYTE
              2. GAMETOPHYTE IS HEART SHAPED

         a. ANTHERIDIA ARE LOCATED NEAR THE "POINT"
            OF THE HEART
                       b. ARCHEGONIA ARE LOCATED NEAR THE "NOTCH"
            OF THE HEART

LIFE CYCLE

1. HAPLOID SPORES GERMINATE AND FORM A PROTONEMA
   (1N)

2. PROTONEMA DIFFERENTIATE AND FORM A HEART-SHAPED
   GAMETOPHYTE

3. EGG AND SPERM FORM

4. SPERM SWIMS TO EGG AND FUSES TO FORM A DIPLOID
   ZYGOTE

5. DIPLOID ZYGOTE DEVELOPES INTO A SPOROPHYTE

ECONOMIC IMPORTANCE OF SEEDLESS

VASCULAR PLANTS

1. FOSSIL FERN SPORES USED TO INDICATE DEPOSITS OF
   FOSSIL FUEL

2. HOUSEPLANTS AND GROUND COVERS

3. EQUISETUM USED TO SCOUR POTS AND POLISH BOWS AND
   ARROWS

4. LYCOPODIUM SPORES USED AS FLASH POWDER BEFORE
   FLASHBULBS

5. AZOLLA USED FOR FERTILIZER, IN CHINA