Let me start by saying that Texas olive (Cordia boissieri) is not actually an olive at all, but is part of the borage family, Boraginaceae. It received its common name because its fruit looks like an olive. Sadly, the fruit is not palatable for humans, but birds and other wildlife like it a lot.
This is a fast-growing shrubby tree, native to Mexico and extreme southwest Texas, which can attain heights up to 30 feet tall with an equal spread. It will probably stay smaller in our more northerly region as it is frost-sensitive and may temporarily burn back to the ground if temperatures go into the teens. With this in mind, it is ideally planted in a sheltered spot with a southern or western exposure, away from cold winds, for maximum winter protection.
Texas olive is highly admired for its handsome dark green foliage and abundant clusters of large, yellow-throated, white flowers. Hummingbirds, butterflies and other insects love the nectar-rich flowers, which can appear from March through December. Although it is very drought-tolerant and grows well in dappled shade, it produces more flowers if given even moisture and full sun exposure. It is not bothered by any major pests or diseases.
It is a great selection for smaller spaces too; train it as a tree or, if grown as a shrub, cut it back to ground level in May and it will quickly regrow and start flowering by mid-summer.