Ask Mr. Smarty Plants

Actually, x cuprocyparis leylandii, (Leyland Cypress) is not native to anywhere; it is an accidental hybrid between a Cupressus macrocarpa (Monterey cypress) and Cupressus nootkatensis (Alaska cedar) when they were both in an English garden in the 1800's. The hybridization would have never happened otherwise, because the native areas of the two were 400 miles apart, in North America. Even if they were native to Texas, we would not recommend their use; see these two websites on the subject:

From About.com: Forestry Reconsider Planting Leyland Cypress in your Yard.

North Carolina State University Plant Pathology Extension Diseases of Leyland Cypress

We will try to find you a shrub or tree that would help dull the noise from the freeway, and we can certainly understand why you want it to grow FAST!  Unfortunately, like the Leyland Cypress, fast-growing trees tend to be short-lived, to break down easily and sometimes do not have sufficient roots to support the extra height in a storm. You need something dense and evergreen, because the freeway still runs in winter, when the leaves are off deciduous plants. Some of these are classified as shrubs, some as trees. Unless you have a solid, noise barrier fence at the back of your property, you will probably not want to trim these up into tree form, but allow them to grow branches up from the ground. All are evergreen and native to the Houston area, and all grow within the stipulated ranges. Follow each link to the page on that individual plant for more information on its culture, bloom time and moisture requirements.

Sound barrier hedge plants for Houston:

Gordonia lasianthus (loblolly bay) - ranges from 30 to 80 ft

Ilex vomitoria (yaupon) - 12 to 25 ft. tall

Ilex opaca (American holly) - 20 to 60 ft.

Juniperus virginiana (eastern redcedar) - 30 to 40 ft.

Magnolia grandiflora (southern magnolia) - to 50 ft. tall

Magnolia virginiana (sweetbay) - 12 to 20 ft. tall

Prunus caroliniana (Carolina laurelcherry) - 15 to 20 ft. tall

From our Native Plant Image Gallery:

Gordonia lasianthus

Ilex vomitoria

Ilex opaca

Juniperus virginiana

Magnolia grandiflora

Magnolia virginiana

Prunus caroliniana