I found an amazing legume resource, but first some background.

When I was taking my online Permaculture Design Certificate course, Geoff Lawton had suggested a book:  “Legumes of the World”.

Why is this so important?  Legumes are species like peas and beans that are considered pioneer species.  There are also legumes that are trees.  These are very hardy and grow in conditions that are not as favorable to other plants.  Some  legumes are “nitrogen fixers”.  They will add nitrogen into the soil while they are alive.  There are other species that will add the nitrogen when they die.  Legumes will interact with beneficial bacteria in the soil.  They will form nodules, little white or pink balls, on their root system that trade starch produced by the plant through photosynthesis for nitrogen from the bacteria.  You can also encourage nitrogen release by cutting the branches of legumes before the rainy season and laying them down on the ground.  As these branches decompose  they will amend the soil.

Since legumes are pioneer species, they will grow in poor soil conditions and areas affected by adverse weather.  They will help repair the soil over time giving way to other species.  For example, the mesquite tree can have a tap root that will go down up to 190ft.  This allows it to be very drought tolerant by reaching water tables in some areas.  It will then be replaced by a taller tree.  Legume species are also fast growing and can provide a wind break or you can companion plant them with younger plants and trees.   I have some pear trees that I planted earlier this year.  Unfortunately I should have planted a support tree with them.  They were very late bloomers and have suffered for it from the Texas sun.  If I had a Russian olive or an Autumn olive planted with it they would have helped to shade these young trees from the sun.

As promised the website.  I would recommend using the common name index.  Have fun identifying legumes in your local area.

http://www.kew.org/science-conservation/research-data/resources/legumes-of-the-world

The same people that wrote the book, converted it into a quick access website.  Enjoy!