Have you considered brazillian pepper? it's available at most nurseries, is evergreen and lush, does quite well in our climate. I am like you - I have the desert xeriscape in the front and want/have the lush oasis in the backyard... I would not go with any of the desert trees if you are looking for something lush green.... ficus is really a big gamble outside of central phoenix/tempe areas... it will not survive temps below 32F.... a few years back we had a devastating freeze which took out many of the ficus throughout the valley except in the warmer "core" of the city.... keep in mind that kind of a freeze happens maybe once in 50 to 100 years out there and you could go with a small ficus and be ok for decades... it's just a gamble.

Instead of a single tree, how about a hedge of some type. I am thinking specifically of Italian Cypress. Italian cypress will grow straight up. While mature ones can get pretty tall, but they aren't much more than 6' wide. That way, it will be able to maximize the space you have available. A couple of other suggestions for small trees are the flowering plum (15-30' tall--12-15' spread), pomegranite, and the fig tree. The latter two are quite drought tolerant and the fig and flowering plum are both decidious. Vines and shrubs can be trimmed as trees. Some of these choices include pyrocanthea (sharp thorns, white flowers in spring and red berries in the fall), Duranta, yellow oleander (Thevetia peruviana), and even orange jubilee (Tecoma sp). Good Luck and HTH

You could consider cypress, especially a new-ish cultivar called Monshell or Tiny towers. It is not tiny -- reaches 30 or 40 feet in height (as opposed to the 100-foot height of a traditional cypress). It stays very slim, only four to six feet in diameter. But a trellis might be more practical in regards to roots. pyracanthus has glossy evergreen leaves that absorb glare, takes brutal sun, is frost proof, has bland white flowers in spring, gorgeous non-toxic berries in fall, and can be pruned or shorn to keep it flat, if you need to walk back-and-forth in that area. It does have thorns, which is why you'd want to keep it in bounds. It is not without some shedding, but nothing that will make you as crazy as bougainvillea blossoms blowing into the water. Good luck finding the right solution!

Lush in the desert is not impossible, especially if you are willing to drag out the hose and water once or twice a week to get things established in their first year or two (a task best done at dawn at this time of year). With no picture, it is hard to make suggestions. One approach would be to plant a grove of trees, and then mix in some shrubs, and then under-plant the trees with some smaller plants. I'd start with trees, both for general effect and to shelter smaller plants. If you must phase planting for budget reasons, definitely start with trees. Here are some ideas to get you started. Trees: Velvet mesquite (Prosopis velutina) can be quite lush in summer, and is only semi-deciduous (the leaves thin out in winter, but it does not go completely bare). Honey mesquite (Prosopis glandulosa) has a more open airy form. With no irrigation in winter it can be completely deciduous, but with some year-round water it can be evergreen. Chilean mesquite (Prosopis chilensis) crosses readily with other mesquites, so it is hard to say what kind you are really getting. but, in general, it has shiny dark reddish bark on the the twigs, and fewer and longer thorns than other mesquites, and there are some hybrids or crosses with no thorns. They are quick growing, even more so with some watering during the warm season. Sweet acacia (Acacia farnesiana) is airy and open and covered with heavily-perfumed yellow blossoms in late winter. Mastic tree (Pistacia lentiscus) is an evergreen with very dark foliage, very tough even in brutal sunlight. Be very specific about the Latin name when buying this one, as other types of pisacia gets huge and needs a lot of water. Texas Ebony (Pithecellobium flexicaule Also known by Ebenopsis ebano) has lush dark evergreen green leaves, pale grey bark. Palo verde (Parkinsonia florida) are everywhere for the good reason that they flourish here. They are essentially leafless (they photsynthesize through their green bark), but make a pleasant very bright shade under which other plants can thrive. And they are blanketed with yellow blossoms in April. Texas olive (Cordia boissieri) is a handsome tree with large leaves. In spring it produces clusters of trumpet-shaped blossoms with golden throats, and then produces a fruit that looks a bit like an olive. Mexican buckeye (Ungnadia speciosa) is a little-known but charming small tree. Its leaves turn pretty yellow in fall, and the bare winter branches have curious nut-like seed pods that are shaped like sleigh-bells. In spring, pink blossoms emerge directly from the bark, and then it is clothed in leaves again. Note that most desert trees have a tendency to grow multiple trunks with branches that sweep down toward the ground. They really can be oversized shrubs. But if shoots are snipped away from the base, they can be trained up into trees high enough to walk under. Shrubs Yes, there are shrubs that can do okay in the desert. Leucophyllum do well in full sun. They go under various names such as Texas ranger and New Mexico Sage. Some species have medium green leaves, others have silver leaves. During monsoon humidity they bear flushes of pink or lilac blossoms. Another full-sun shrub is little-leaf cordia (Cordia parvifolia). It has a large open airy arching form, pale grey green leaves. In the most brutal hot weather it produces delicate white blossoms of purest white, with a slightly crumpled crepe like form. Dalea comes in many heights that range from knee height at maturity, to shoulder-height at maturity. They have millions of tiny evergreen leaves, and produce many small panacles of blossoms in various shades of violet. There is one yellow-blossomed short type (can't remember the name), and there is tall bluish lavender fall blooming type called Monterey blue. Desert butterfly bush (Buddleia marrubiifolia) does well in blistering sun and heat. It has silvery leaves, and little button-shaped blossom heads of golden orange, that are scented like saffron. It grows about should height. Senna (Senna artemisioides and others) do well in severe desert sun. There are several kinds, most introduced from the deserts of Australia, but not invasive. Choose a type with the leaf form you like best: feathery, blade-like, or knife-edged. They produce quantities of waxy bright yellow flowers in very early spring. Mexican bird of paradise (Caesalpinia pulcherrima) may seem common, but a big healthy plant gives a nice lush look, almost tropical. Once established, it can be cut to the ground every fall and it will produce denser growth each successive year. Chuparosa (Justicia californica) is not considered a very impressive plant, but I would not be without it. It has long spindly pale green stems with a few leaves in summer. Then, in winter when it is leafless, it produces tubular scarlet blossoms for months, which are visited by hummingbirds non-stop. The above shrubs flourish in blazing desert sun, but if they are gradually shaded by trees growing up around them, they keep performing well, though some will produce leggy new growth. Shade plants: Once you have some shade established, you'll be able to grow some shade-preferring shrubs. Yes, there is such a thing. Here are a few of my favorites: Mexican honeysuckle (Justicia spicigera). It has light bright green leaves, and tubular orange blossoms (great to attract hummingbirds). When you see it in a nursery you may recognize it as a plant that looks unhappy around gas stations. This is because it is unhappy in full sun, and developes an ugly broom-like stiffness if shorn. Just let it grown naturally and it is quite graceful and charming. Turks turban (Malvaviscus arboreus drummondii) likes summer shade and winter sun, so it succeeds if planted just under the south edge of a tree that will shelter in from summer midday sun and winter frost, but where the low winter sun can reach it. It has broad papery evergreen leaves, and in fall produces little spiral scarlet blossoms that continue until frost (through frost if you cover it). Mexican dioon (Dioon edule) is a silvery-green version of the dark green tropical pineapple palm (a.k.a. sago palm), but it is well suited to our desert climate, unlike its tropical cousin. It does well in a very bright filtered light such as under an acacia or palo verde. Wandering Jew (Tradescantia pallida) now sold as purple heart, is a native of Mexico, does will in our desert, and add colored foliage. It can be used as a ground cover, but I find its tumbling habit is best shown off in a pot or even in a hanging basket among the tree branches. It gets a little beat-up looking by late winter; I just cut it back and new growth comes in rapidly. I ordinarily would not recommend a tropical plant for the low desert, but I love star jasmine (Trachelospermum jasminoides) and it does well in bright shade, for example against a north-facing wall. Once established, it can get along with only a little water; this may produce a sparse plant, but the blossoms are just as intoxicating each spring. Cacti and Succulents The above list can give an overly-shrubby unstructured result. Some definition and structure can come with cacti and succulents. Oddly, cacti and succulents can contribute to a lush tropical look when planted under trees and among shrubs. Almost all cacti and succulents prefer afternoon shade or dappled shade. Those with a lot of all-over thorns can end up getting rather cluttered with leaf debris. It doesn't bother the cactus, but it may look messy to you. At any rate, when introducing cacti and succulents consider a mix of forms: posts, spheres, starbursts, spindles, paddles. For posts, look to totem pole cacti, mexican fencepost cacti, peruvian apple cacti, golden torch cacti. These all get anywhere from five to fifteen feet tall. For spheres, look to barrel cacti. Golden barell and red-hook barrels stay very spherical and the color of their spines is beautiful with the low morning or evening light streaming through them. For starburst shapes, consider any of the many many forms of yuccas, desert spoon (Dasylirion wheeleri), and any of the many many types of agave. They grow to differeing mature sizes, so research the peak size of the kinds that interest you. Note that with Agaves you can snip off the last quarter inch of the black spines so they are not quite so lethal. A few aloe plants are pretty much frost-proof. They look a lot like agaves but pointed tips are not as forbidding, and they produce interesting pinkish-orange flowers every spring. Among the tougher ones are Aloe ferox and Aloe vera. Although they can take a lot of direct sun, they seem happier in bright dappled shade. For spindle forms there is slipper plant (Pedilanthus macrocarpus), a collection of leafless 9or almost leafless) slighly wobbly waxen green sticks that produce curious pinkish-orange blossoms in the heat of monsoon season. They can reach six or eight feet in height, and fairly quickly send up additional shoots around the periphery to produce more and more spindles. If grown in shade, the nearly-straight spindles take on wonderfully crooked and swoopy shapes. Another spindly shaped plant is cadellila (Euphorbia antisyphilitica). It produces dense clumps of pencil shaped stems that reach only about ten or fifteen inches in height. In early summer they are covered with minascule greyish-pink blossoms. Given their diminutive height, I grow them in pots in full desert sun. Paddle cactus are the many types of prickly pear or Opuntia. The kinds that arch down and touch the ground take root and often become impenetrable havens for pack rats and mice (which equals snakes). Look for ones with an upright growth habit, or take off paddles before they touch the ground, easily done with the fireplace tongs or a dedicated garden set of kitchen tongs. Look for shapes or colors that interest you (the santa-rita prickly pear is purplish; the beaver-tail prickly pear is almost blue). Gopher plant (Euphorbia rigida) is a north African plant, and not actually a cactus. It grows in blistering sun, reaches about fifteen to twenty inches in height. In spring it produces heads of chartreuse blossoms. As they finish blooming, the stems die and need to be sliced out just as new stems emerge, an annual ten-minute task. Well, these are just a few tips to get you started. If you use a rake or hoe to pull surface soil inward around a new plant to form a ring-shaped dike, it makes weekly watering with a hose easy cuz the water stays where you want it. Look up each of the plants listed above, using the full two-word Latin name in quotation marks to get you to the intended plant, and then you can see pictures and read more about origins, care, size, soil, etc. By way of inspiration, here is a photo of what I did with my desolate back yard of beaten dirt and rock, using desert plants. (if the photo loads).