This is a small tree version of the Ochna I posted recently. Known as Ochna integerrima (common name: Vietnamese Mickey Mouse Plant; Family: Ochnaceae), the ones planted at HortPark's Floral Stitches have an almost non-existent crown with few leaves. One of them was in flower recently and these are the photos taken just days ago.
During the Chinese New Year a few years ago, this plant was sold as a small bonsai-like plant under the name 满地黄金, which translates to floor of gold, presumably because of its yellow flowers. However, it didn't quite catch on.
Some links are attached here: