FERNS

Phylum Pterophyta

HOW DID WE GET HERE? Evolution is the derivation of progressively more complex

forms of life from simple ancestors; Charles Darwin proposed that natural selection is the principle mechanism by which evolution takes place.

NATURAL SELECTION Natural selection is the gradual, non-random process

by which biological traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution.

The term "natural selection" was popularized by Charles Darwin who intended it to be compared with artificial selection, what we now call selective breeding.

PHYLOGENETIC TREE

SIMPLE PHYLOGENETIC TREE

DETAILED PHYLOGENETIC TREE

COMPLEX PHYLOGENETIC TREE

THE STEPPING STONES From the somewhat simple Bryophytes…

To Phylum Rhyniophyta and Phylum Zosterophyllophyta Both have no living species - only known through the fossil record

Phylum Lycophyta (club mosses) Phlyum Psilotophyta (whisk fern) Phylum Sphenophyta (horsetails) Phylum Pterophyta (ferns)

Order Ophioglossales ( Order Marattiales (

Adaptations along the way: Polysporangiates (branched sporophytes, dominant sporophyte generation) Tracheids (internal wall thickening = earliest vascular tissue)

Specialized water conducting cells

MAIN FERN FEATURES Without dichotomous branching Differentiated into roots, stems and leaves Spores can be homosporous (bisexual) or

heterosporous (microspores/male and megaspores/female)

Megaphyll leaves (veins and leaf gaps) Protostele (single column of vascular tissue) Sporangia on sporophylls = fertile fronds

(some clustered in sori)

LIFECYCLEOF A FERN

ADULT SPOROPHYTE Underside of Leaf (megaphyll)

Close up of sori (sorus) below

Indusia are special outgrowths of the leaf to protect the sori

MATURE GAMETOPHYTE The prothallus (haploid = cells with one set of

chromosomes)

WHAT LIFECYCLE PART IS THIS????