### plant part | root:

Plant root
* Most plant roots absorb nitrate
  - water
  - go much deeper
  - take up water
* Plant Roots contribute astonishing quantities of organic matter and put it directly in the soil.
* Some plant roots grow in water.
* Some plant roots provide habitats
  - microbial habitats
  - prime habitats
* absorb carbon dioxide needed for photosynthesis from the soil
  - three vital nutrients
* anchor the whole plant, absorb water and nutrients.
* are able to follow the worm holes and go deeper down then with plowing
  - penetrate soil deeply for extended drought resistance and stability
  - very shallow and easily damaged by excessive rates of certain herbicides
* begin to stabilize the soil against erosion.
* break up the surface of a rock allowing water to penetrate the cracks.
* can absorb sodium and transport it to leaf tissue where it accumulates
  - extend into fractures and grow, causing expansion of the fracture
  - only grow in moist soil so root tends to follow the water gradient
  - penetrate easily to deep levels and withdraw enough soil water from there
  - use it for their growth
* create a zone of nutrient depletion around themselves.
* display very sensitive growth patterns to a range of chemical and gravitational stimuli.
* do the same thing, they hold the soil together.
* fail to thrive in wet soil so drainage is very important.
* function like a water pump, taking minerals and nutrients to every part of the plant.
* grow into cracks in rocks
  - the pumice, where they act as filters and oxygenators
  - within the active layer, and insects burrow here
* growing in cracks and breaking the rock apart is another example of physical weathering.
* have a difficult time extending into soil that has little air space
  - hard time adapting to the native soil outside of an amended planting hole
  - difficulty extracting water from the deeper layers of clay-textured soils
  - to grow to find the inorganic nutrients that the plant needs to stay alive
* help to stabilize the sand
  - water to drain or percolate into the soil
* keep the rocks or soil loose so that water can flow through easily.
* obtain nitrogen as nitrates and ammonia from the soil.
* occur in litter, humus, and upper mineral layers.
* penetrate good soil deeply for extended drought resistance and stability
  - soil, creating excellent water channels when they die and rot away
* play an essential role in soil development and prevention of soil erosion.
* proliferate through the soil using the burrows as easy passage.
* require oxygen for growth so adequate aeration of the medium is necessary
  - in order to take up the water
* rot and suffocate from too much water and too little air.
* stabilize soil and prevent erosion.
* suffer from oxygen starvation and clay also binds water, causing plant roots to rot.
* take in or absorb nutrient ions, whereas soil colloids adsorb ions
  - oxygen and give off carbon dioxide
* take up their silica as silicic acid
* undergo tension as they pull the water out of a soil matrix.
* uptake water from the surrounding soil through osmosis.
* use a chemical compound in solution which is taken up from the soil particles.
* wear thin or thick-soled shoes according to the rugosity of the soil.
+ Arctic, Plant life
  * Each summer the ice and snow will melt, allowing the animals to find food and the plants to flower. The moisture from the snow stays toward the top of the ground's surface. Plant roots can use it for their growth. Even so, in many places the soil is too poor for plant's growth. Less than half of the tundra has plants growing on it.

Plants root
* grow downward toward water.
* suffocate and rot in it.

Pneumatophore
* are almost hollow, allowing air to pass to the living tissue of the root
  - essentially the erect lateral branches of an otherwise horizontal root system
  - normally unbranched
* often present.
* take in oxygen from the air unless they're clogged or submerged for too long.