Capparis spinosa, the caper bush which has edible flower buds and fruits that gives capers.
I’ve only seen a few of this plant here in Cyprus unlike in Malta where it’s very common.
The plant, also called Flinders Rose, is very useful. The buds and its fruit are usually consumed salted or pickled as a part of the Mediterranean diet. Each flower usually lasts only 24 hours, but there is a continual opening of flowers along the stem. It’s a very special bush with beautiful bright flowers.