Sinapis alba is also known as white mustard. Yes, it is mustard but why call it white? It is a carpet of yellow. The white refers to the seed, but even those aren't really white, they are more of a light brown.
When tourists in Cyprus comment on the fields of rape, this is what they are seeing: a field of a weeds. It did use to be grown commercially for its seed but nowadays mustard is obtained from other species which are easier to crop. So white mustard is now relegated to weed status in spite of its uplifting show of colour in the spring.
Photo by Lez
It has a relative in Cyprus, S.arvensis which looks similar. Its name means "of ploughed fields" and indeed that is where both plants can be found : in recently ploughed olive groves. Most olive groves used to be ploughed annually, but this is not so much the case now in North Cyprus where an olive tree is no longer a valuable asset.
S. alba grows intermingled with the rampant Oxalis pes-caprae which has the same yellow flower colour. This really is a weed. Everyone would like to eradicate it, but no one can. It grows from small bulbs that are relatively deep in the soil, attempting to unroot the plant breaks off the stems but leaves the bulbs undamaged. Where the weed becomes established the ground is riddled with these bulbs.
Photo by Lez
Left: plant showing the thin stems joining to a stouter root that arises from tiny bulbs. Above: the flowers.
Oxalis pes-caprae probably originated somewhere in Africa. Sinapis alba probably originated in the Mediterranean region. In the photograph below you can see the small seed pods, each containing about 6 tiny seeds. Imagine the labour needed to harvest enough to make a decent pot of mustard.