Thin-Leafed Alder

Plants in order to thrive need the three nutrients we see on fertilizer bags, Nitrogren, Potassium and Phosphorous. (the N, P, and K). and some secondary nutrients and trace elements.
Some plants actually feed the nitrogen into the soil on their own. These are primarily legumes., but there are some from some other plant families also. The nodules on the roots of these plants form a symbiotic relationship with some fungi and some bacteria. These convert the nitrogen in the air into organic compounds. It is called nitrogen fixation. These plants can obviously thrive in nitrogen poor soils. Some of these plants are beautiful. Lupine with flower spikes up to five feet tall is one of these.
Nitrogen helps with photosynthesis, and is part of the plant structure leaves, grains, roots and plant tissues. It also helps plants take up water through their roots.
Some more plants that grow in poor soil are, Alder, Wax Myrtle, White Clover, Wild Indigo, and one of my favorites Wild Lilac.