How are plants adapted to their surroundings?

Trample-resistant plants

→adjustment to frequent trampling

• grow from the bottom (other plants grow from the top) → mowing → growpoint not damaged

• leaf position = vertical → no direct sunlight on leaf →protection overheating + more leaf area per m² → more optimal photosynthesis →grasses grow faster

• dense and shallow root systems → to store H2O + nutrients →if parts above ground are damaged →fast regrowth →reserve H2O + nutrients

Succulents

→adjustment to drought

• stem succulent example: a cactus

  • stem → ability to store water

  • leaves = needles → smaller leave area →limiting evaporation

  • thick wax layer → limiting evaporation

  • deep and well-branched roots →absorb more water from a bigger area

  • white hairs

    • reflecting sunlight → preventing overheating

    • retains air layer → isolation → limiting evaporation

    • retains dew and raindrops → water goes into the ground → roots can absorb it

• leaf succulent example: Aloe Vera

  • thick wax layer → limiting evaporation

  • less stomata → limiting evaporation

  • stomata is deeper in the leaf→ preventing dehydration

Halophytes

→ adjustment to high salinity

without any adjustment → osmosis → H2O goes out of the plant → plant dies

osmosis = the movement of water molecules from a solution with a high concentration of water molecules to a solution with a lower concentration of water molecules, through a cell's partially permeable membrane. Until they the amount is equal on both sides

2 solutions

1. concentration of salt plant cells >>> concentration of salt soil → plant can absorb H2O

   example: samphire = a salt-tolerant succulent

2. salt glands on leaves → secrete excess salt

   example: mangrove

Carnivorous plants

→ adjustment to poor soil

example: Venus fly trap (= VFT)

• nitrogen-poor soil → VFT cannot fixate enough nitrogen → no assimilation of protein compounds →shortage nutrients → compensate it with digesting insects

• attracts insects by secreting nectar-like substance

• reproduction → grow a flower on a high stem above the leaves → no danger for insects → insects can pollinate → forming seeds → flower dies

Adjustment to light competition

• growth speed

  grasses = fast growers →take away light herbaceous plants → development of rosette =

  a circular arrangement of leaves or of structures resembling leaves →ground cover → grasses can’t grow

example: plantoga major, daisy

• growth period

  forest herbs growth is in spring → almost no competition → summer → dense foliage → stops sunlight → after seed forming → the plant dies above ground →made enough nutrients during spring → stored in rhizomes

• growth direction crown

  to lessen competition → plants grow in other direction → depends on place example: oak

  • open field

    • wide

    • branched

    • symmetrical

  • forest

    • less side branches

    • grows in height

  • forest edge

    • asymmetrical

    • grows to the edge of the forest

• leaf mosaic = the arrangement of foliage in most plants (as in the common ivy) in such a pattern as to expose the maximum number of leaves to the direct rays of the sun with little loss of intervening space.

Epiphytes

epiphyte = an organism that grows on the surface of a plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it.

example: orchids