Earth Science: Seed Plants – Habitat Specialists
Plants use specific strategies to adapt to their environment. Climate conditions and the availability of water and nutrients, all affect their structures.
Essential dissolved minerals for growth and metabolism include nitrogen, phosphorous, calcium, magnesium, and iron. Potassium in particular is required to control the microscopic, pore-like openings of the stomata.
These minerals are generally taken up by the roots, in the form of ions. In many cases plants have a symbiotic relationship with bacteria or fungi in the soil, increasing the roots available surface area and in turn providing the bacteria or fungi with sugar, a product of photosynthesis.
Nitrogen fixing bacteria are also important in helping plants obtain molecular nitrogen.
Adaptation to temperature and moisture conditions
Optimal levels of resources for growth are not always available, therefore plants have adapted to survive a wide range of environ- mental conditions. They have many different strategies related to coping with water loss or excess in various extremes.
In hot, dry environments plants reduce evaporation; mosses and flowering desert plants dry up and retreat into a dormant state and succulent plants store large amounts of water in their shoots and leaves, which they release only sparingly during droughts. Others minimize evaporation by having fewer or smaller leaves, or by growing deep root systems that spread out to absorb as much water as possible.
In moist environments, plants increase evaporation of water from their leaves (transpiration) by developing broad, thin leaves with mini- mal or no waxy coating. In variable climates that include periods of frost, the majority of plants shed their leaves in winter or produce a natural antifreeze substance that prevents ice crystals from forming in their cells.
Aquatic plants, on the other hand, absorb water and dissolved minerals over their entire surfaces and therefore only have weak roots. Conversely, plants adapted to low light conditions tend to have large leaves with high chlorophyll concentrations in order to photosynthesize more efficiently.
SALT PLANTS
Salt plants populate salty habitats, either dry or flooded, often near a salt lake or the ocean Some species may grow in either fresh or saltwater. Others prefer saltless ground but have been banished by competing plants. Yet others not only tolerate, but thrive under saline conditions.
Salt- excluding species pre- vent salts from entering their tissues through reverse osmosis. Salt-excreting species are able to take in highly saline water through their pores, and excrete excess salts through specialized glands in their leaves.