I saw this evergreen plant today and have no idea what it is. The foliage appears to be phyllodes rather than true leaves and the flower bud are very tiny. The overall appearance is a bit like some of the acacias, but the size of the flower buds and the style of the young growth around them less so. Considering the planting theme of the part of the botanic garden where it was growing, I'm wondering if it may be South American?
No, that's a plant I'm very familiar with. Its foliage is less lustrous, more rounded at the tip and it has been in flower for a couple of weeks now while this has a while to go before blooming. It doesn't really "feel" like an acacia. Just not quite right.