Answer: There are two excellent types of citrus for your area. The hardiest of the two is the Kumquat. This may be the "bushy" one you referred to in a neighbor's yard. The fruit is small (about 1 - 1 1/4"), with an edible skin. Kumquats can take temperatures down into the mid to lower 20's before suffering damage. Look for the variety 'Meiwa'.
The second type of citrus is the Satsuma orange. Satsumas are mandarin type oranges with loose, easy-to-peel skins like a tangerine. They are hardy to the mid 20's once established. The trees are fairly small statured. I have seen 8 year old trees not over 6-8 feet tall. Satsuma varieties to look for include 'Armstrong Early', 'Owari', and 'Kimborough'.
Both citrus types are easy to grow but require good drainage. On a marginal soil, a raised bed is a must. Scale and whitefly are about the only problems you will encounter in your area. Both are controlled with oil sprays, and Neem is another option for the whiteflies.
I would recommend you call local nurseries for sources of these plants. They are not common in the mail order trade and many Houston area nurseries sell them. Good luck with your citrus.
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