one of several species of Mimosa. Perhaps a prostrate mimosa, like Mimosa strigillosa, or the larger Mimosa pudica or Mimosa sensitiva. None native to Taiwan as far as I know.
Another choice is Chamberbitter (Phyllanthus urinaria). The true Mimosas have small purple pom-pom type flowers, the niruri or chamber bitter has greenish white, minute flowers that appear at axils of the leaves, with the seed capsules found under the leaves. The leaves are also sensitive.
The presence of thorns on the previous photo makes me think of a true Mimosa instead.