Eating on the River Walk can be a bit, well, undignified and even raucous, but never here, where decorum rules. The menu’s style changes from time to time; right now it is straightforward and modestly upscale, with beef dishes (including beef Wellington and tournedos Rossini), trout, salmon, scallops, and chicken. Spotless white tablecloths mark the snazzy interior, while adroit servers keep an eagle eye on tables. Watermelon figured in both an appetizer soup (very cooling, and neither sweet nor savory) and a perky salad with mint and cheese. Both the salmon and the shrimp and scallops with linguine showed firm control in the kitchen; they were moist but cooked thoroughly. In short, for a fancy evening on the River, the Tree can be a smart choice. Bar.