Ask Mr. Smarty Plants

This USDA Plant Profile map on  Bauhinia lunarioides (Anacacho orchid tree) does, indeed, show that it grows natively somewhat south and west of Llano County. On the other hand, on our Native Plant Database page on this tree, we found this information:

"Native Habitat: Canyons & arroyos in limestone hills. Known only from canyons and arroyos in limestone hills in Kinney, Presidio, and Gillespie or Llano counties. Well-drained sand, loam, limestone." We didn't find the previous Mr. Smarty Plants answer to which you referred, but several other websites we looked at specified full sun, reflected sun or part shade.

Since you already have the plant, and since there seems to be more danger of frost damage than of too much sun, we would suggest you go ahead and use your described area. We consider part shade to be 2 to 6 hours of sun a day, so if there are a few hours of shade in the area, the tree should be all right.

As with all desert plants, the most important thing to consider about this plant is good drainage. In Texas, we recommend that woody plants not be put in the ground until cooler weather, to help prevent transplant shock. Since you already have your plant, we hope you are giving it some shade every day, and watering in a well draining pot. Those black plastic nursery pots in the sun can really heat up the soil and roots inside! It is best to prepare the hole ahead of the actual planting, add a good mix of compost to the resident soil to help with drainage and assist the tiny hair-like rootlets that access nutrients and water in the soil for the whole plant. When you remove the tree from its pot, check to make sure the roots are not wrapped around, threatening to strangle the tree. Some fairly vicious root clipping may be required before the tree goes into the ground, so the roots will start growing outward again. After it is in the ground, water by sticking a hose down in that nice soft soil you have made, and let the hose dribble for half an hour or so. As long as we continue to get no rain, this should be repeated weekly. No fertilizer. This plant does not particularly like fertilizer anyway, and it can shock those newly sprouting roots.