There are many trees in the legume family (fabaceae) - acacias, locusts, redbuds, and yellowwoods, for example. Did the garden book give any other details?

Am I correct in assuming that legume trees all have long seed pods? If that's right, most of the native trees here in south tx are in the legume family--mesquite, etc.

Honey locust grows to the appropriate size for this purpose and creates a dappled shade, because of its finely divided foliage.

Black locust provides a similar partial shade but some people dislike the way it self propagates from roots and seeds. It's somewhat invasive. It grows to a large size eventually.

Redbud is a small ornamental which blooms in the spring. It's not large enough to create a canopy.

Those are the only ones I'm familiar with and I don't know if they are suitable for your climate. But it's a start.

Jim

Silk trees(pink mimosa) are between locust and redbud- invasive from seed, will grow to large size but can be kept small by pruning to multiple trunks, but they split and shatter and leave a mess with their linbs falling

I have to comment that this advice seems ill-fated, considering the tendency of so many of the Leguminous trees to be soooooo weedy (seed prolific or root suckers).

If you are going to seriously investigate this, I'd suggest that you either let us know where you are located so that we can comment on the fate of some of these trees in your area OR do some serious research yourself.

I believe the reason for the legume trees was to add nitrogen to the soil. I'm hoping to have a veg./herb garden in raised beds to the west of my house. It's full sun with temps over 100 during the summer. The native area around here is full of thorned shrubs and trees. I had raised veg. garden beds at a previous home in a different zone. They were great for a couple of years, then became full of roots from willow trees nearby. Don't want to have that problem again. The soil (what there is of it) is caliche and rock. That's the reason for raised beds.

I'd go for a honeylocust, not only does it fix nitrogen but it doesn't sucker much and if you go for a wild type tree you can consume the sweet pulp of the beanpods and the spines can be used as nails if your in a pinch and dealing with soft wood.

I was wondering why anyone would want to have a tree-canopy on the West side of a garden (or any other side); in our zone 7, Maryland, area, we want FULL sun on warm-weather crops, completely unobstructed by any tree canopy. I'm guessing you're in an area that is TOO hot, and you want shade from late afternoon sun??
Also, as much as I like Mimosa--particularly as a Hummingbird attractant--they're considered an invasive in my state, and, no doubt, in most states in the U.S. (since most non-native species trees are). Their seeds get carried far and wide by wildlife. As rhizo suggested, I'd check with my Extension Agent or State Forestry Department before planting non-native trees.

Do the false acacias ("locust") thrive in zone9? I havn't noticed them in the deep south.

Robinia pseudacacia - look it up- does not do well in the south- my recollection is that freezing winter slows down the boring beetles. There is a southern Robinia species with pink flowers that thrives in Texas and Arizona(not sure might be mexicana) I cannot tell them apart but the southern one has pink clusters of flowers(think sweet pea, but edible) and the one here has white clusters of flowers

Golden Chain tree: Beautiful in flower, noninvasive, all parts are poisonous, including the pea-like pods. I grew up with a golden chain tree in our yard and was warned that if I ate the seeds, IÂd croak.

Here is a link that might be useful: Golden chain tree

I will suggest Moringa Oleifera also known as Drum stick tree.It's leaves ,flowers and about 2 feet long fruits (looks like a long bean) are edible. It has many medicinal uses also. Grows very rapidly to a height of 10 to 15 feet.

Others not mentioned would be Acacia (many different cultivars), Eve's Necklace, Texas Mountain Laurel and Kentucky Coffee Tree. I believe all of these will grow in South Texas.

In response to the locust suggestion, I worry that since locusts have relatively weak wood it could really damage anything underneath it if a branch were to break off. You may want to take a look at the Kentucky coffee tree. Its a tall shade tree that would work great for a canopy. Additionally the Kentucky coffee tree doesn't really spread which does seem to be a problem with a lot of other legume trees.

Here is a link that might be useful: Kentucky Coffeetree wiki

I don't know if you are familiar with Plants For a Future (PFAF) but they have information on plants and rate them for usefulness. I searched for seed pods and nitrogen fixers, this list contains herbaceous plants too. I don't know if the legume trees mentioned that are not on the list don't fix nitrogen? One Permaculture concept is to plant in assemblages that benefit each other and use a few nitrogen fixers mixed in.

Here is a link that might be useful: PFAF search

If you are in a hot area you might want to consider one of the species of Palo Verde, Cercidium floridum or microphyllum. They don't cast much shade and as an added benefit their "beans" are very tasty if you harvest them in the early summer, before they begin to harden...