HISTORY OF PLANTS
470 Mill years ago
Evidence sheets of moss on rocks and the edge of water
Journey of evolution - to land
Earth changed from tropical - to seasons (hot cold, dry, wet)
Further adoption to land -climate
Bryophytes
Mosses, Liverwort, etc.
Are used as examples of plants without most modern evolutionary adoption
But: they are not the primitive ancestors of other plants
NOTE: vascular plants came first; non vascular plants came as a branch
Characteristic of Bryophytes
Non vascular plant
Have no veins (vascular tissue)
No roots for penetration of the soil
Are small
Lack support to get big
Parts mostly stay close the ground
So they can get water and nutrients
Other characteristics
No functioning stomata (pores)
They have little control over water loss
Have little or no cuticle
Reproduces via spores (not seeds)
Have flagellated sperm
NOTE: Peat Moss
Genus- Sphagnum-comes from Canada
Agriculture- used as soil additive - retains moisture
Is acidic - prevents seeds form damping off (damping off is a fungus decease)
Also used as fuel
Grows very fast
Does not root
Form mats many feet thick
Make bricks -burn good
Better than wood
Worse than coal
Trends in plant evolution
English: Coconut Palm on Martinique.
Planting corn along a river in Tennessee (LOC)
Prothallus of the tree fern Dicksonia antarctica (...1. better vascular tissue
a. xylems=veins in plants
Carries water
Dissolves-nutrients (N, P, K)
b. "most primitive xylem are called tracheids
Is made out of dead cells
c. advanced xylem -(mixture more vessel elements)
Occurring in seed plants-gymnosperm (no flowering seed plants)
Has a vessel element
2. Unequal branching
a. Earliest vascular plant - no branch
b. Then two branch
c. Then dicatomous branch-equal branching
d. Unequal branching
Get tall faster
More efficiently in food competition
3. Secondary Growth
Growth in diameter (girth)
Through adding layers of xylem
They grow taller
Persist form season to season
Survive from season to season...