The white wall rocket is a very common annual plant, which grows in disturbed habitats such as uncultivated fields and roadsides.

It is native to southern Europe and the Mediterranean but is now found further north and even reached southern England, probably as a result of climate change.

Many species of crucifers serve as food plants for the caterpillars of various species of the white butterfly

Despite, or because of the fact that it is very common, few people actually take enough interest to look closely at the flowers. These are white and sometimes have a tinge of violet.

Their structure is similar to that of other members of the mustard family to which the rockets belong.

It is made up of four petals arranged in the form of a cross.

The family is, in fact, also known as the crucifers, meaning cross-bearing or, sometimes, as the cabbage family.

After having lain dormant for a whole summer, the seeds of the white rocket sprout quickly soon after the first autumn rains. The plant starts flowering within weeks.

The crucifer family is important because several species have been cultivated for thousands of years. Its members include cabbages, broccoli, cauliflower, turnip and mustard. The leaves of the white rocket are similar to those of the cultivated rocket and they are sometimes added to salads to add a spicy taste.

They are said to have diuretic properties but it seems that the plant is not used medicinally.

Many species of crucifers serve as food plants for the caterpillars of various species of the white butterfly, including the small and cabbage whites which can become pests of cultivated plants.

Members of this family are characterised by fruit in the form of a capsule known as a siliqua – an elongated structure with seeds inside. The capsule breaks open along a line of weakness in dry conditions.

In some species, the siliqua breaks open explosively and the seeds are thrown far and wide away from the parent plant.

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