Flowering members of Prunus are probably fine, but fruiting plums are messy and not that drought tolerant. Chilopsis linearis (desert willow) is nice IMO.

{{gwi:521266}}

None of your three choices -- Japanese Maple, Crape Myrtle, plums -- are anything close to drought-tolerant. I am thinking that the Center for Sustainable Energy is not a California organization and is only looking at the fact that the crape myrtle is deciduous (summer cool, winter warmth).

Here's a better start:

Acacia baileyana Bailey Acacia

Aesculus californica California Buckeye

Arbutus unedo Strawberry Tree

Celtis australis Southern Hackberry

Cercocarpus ledifolius Curl-leaf Mahogany

Cotinus coggygria Smoke Tree

Eriobotrya deflexa Bronze Loquat

Feijoa sellowiana Pineapple Guava

Geijera parviflora Australian Willow

Koelreuteria paniculata Goldenrain Tree

Parkinsonia aculeata Jerusalem Thorn

Pistacia atlantica Mount Atlas Pistache

Pistacia chinensis Chinese Pistache

Prunus lyonii Catalina Cherry

Zizphus jujuba Chinese Jujube

And it might help to know what you consider small. A "small tree" is 20-30 feet. Is that "small" enough? Could be you want a large shrub, pruned up as a single-trunked "tree" or limbed up as a multiple-trunked "tree" (some of the above).

Joe

Besides being deciduous and drought tolerant, think about how you will use the area under the tree. How tolerant are you for the droppings from the tree? Will you want to grow any plants under the tree? So often it takes several years to recognize our choice of a shade tree was a mistake. Al

Japanese Maples do better with morning sun/afternoon shade and most certainly are not drought-tolerant. In nature they are an understory tree (a small tree that grows in the shade of larger trees). The foliage gets toasted in full sun unless you are right along the ocean. They are nice in large (watered) pots on a covered patio where they get a little morning sun but shade in the hottest part of the day.

Cercidium, Palo Verde.

You can go with a Loquat they get to about 10ft tall on average.

I planted a Sambucus Mexicana (Mexican/Blue Elderberry) in my front yard in coastal South Orange County and am very happy with the result. Once established, it is drought tolerant, with white flowers in spring and small blue berries throughout the summer. Birds eat most of the berries before they hit the ground. It is deciduous and tops out at about 20 feet in height. Look for it at native plant nurseries.

One note: It must be trained as a tree, as its natural shape is more like a shrub, so it is best to start with a small (1-gallon size) plant. Given plenty of water, mine shot up ten feet the first year I planted it, so it was easy to shape into a tree.

Thanks to everyone for their responses. I guess we have to rule out Japanese Maple since our front yard is south-facing and gets full sun.

We were visualizing a tree with foliage that is full and rounded, and about 5-6 feet off the ground. We don't want anything shrub-like mainly for aesthetic reasons. We'd like the tree to shade the house in the summer and allow the sun to come through in the winter.

Below the tree, we'll have succulents and drought-tolerant plants, with much of the ground cover being pea gravel.

I'm still looking up all the various suggested trees on the web to see what they look like... but please keep your suggestions coming! Also, if you can recommend a good nursery in the San Diego area, I'd appreciate those as well!

I'd recommend Chitalpa. It's a drought tolerant hybrid of Chilopsis, mentioned earlier, and Catalpa. Has the best of both. Long flowering season in the warm months, deciduous in the winter. Well behaved front yard tree. Crape Myrtles are fine....get a mildew resistant variety! Also, there's another, darn, can't recall atm. it's well behaved, drought tolerant, and a distant citrus relative. Used quite a bit in landscapes now. narrow, willowy leaves....it'll come to me

Tree of Life nursery off the 74 is one of my favorite nurseries for drought tolerant plants, 33201 Ortega Highway, San Juan Capistrano.

It sounds like Western redbud is the way to go! Beautiful (and edible) flowers, nice fall color, a great small habit.

An established crepe myrtle at my old house in inland OC received no supplemental water and was fine. I wouldn't rule it out unless you are close to the water where it may mildew. Anything that you plant will need water for the first couple of years.

pop over to Walter Andersen's in Poway or Point Loma and have a chat with them about good choices. The western redbud might be a bit shrubby.

Fruiting Quince

Pomegranate (very ornamental with its fiery orange blossoms and decoratively shaped fruits).

kind of exotic but Yellow Cotton Tree

citrus is fairly drought tolerant, maybe get a Satsuma Mandarin or Valencia Orange tree, or maybe a lemon tree.

My guess is the OP planted a tree about 7 years ago. I wonder what wobsie selected and how it is doing.