There are many plants that fit that set of conditions including trees, shrubs and perennials. Three waterings a week is a lot and in fact once established many plants can go with one or two waterings a week unless the soil is an unimproved droughty sand.
Some plants to consider include: treasure flower, ice plant, New Zealand flax, yellow bird of paradise, lantana, daylily, plumbago, bougainvillea, natal plum, Autumn sage, rosemary, sweet broom and rock rose (Cistus).
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