Takes ammonia and converts it to nitrite ions. 2nd step of nitrogen cycle

Nitrification

Explanation:

The second step in the nitrogen cycle, where ammonia is converted into nitrite, is called Nitrification. This process takes place in the soil, due to the action of nitrifying bacteria, called Rhizobium. These bacteria act in two stages: The first stage is called Nitrosation, where the ammonia oxidized to nitrite is absorbed, almost completely, by the vegetables present in the soil. The second stage is called Nitration, where nitrites are released into the soil to be oxidized again.

the dark variety, as they are not visible on the dark tree barks

explanation:

desert perennials often survive by remaining dormant during dry periods of the year, then springing to life when water becomes available. most annual desert plants germinate only after heavy seasonal rain, then complete their reproductive cycle very quickly.