About
London rocket is a common, annual Mediterranean ‘weed’ species and normally requires some summer sun and heat to produce seeds. It is unknown when London rocket was first found in London, but it was known to be plentiful at the time of the Great Fire in 1666. Its presence was sparse and sporadic across the rest of Britain and is thought to have benefited from the warm city centre. After the Great Fire, the plant slowly dwindled in its distribution and may have become very isolated or even disappeared.
History
London rocket was re-discovered in 1945 in gardens near the Tower of London, and still clings to parts of the London Wall at Tower Gateway. In 2010, several plants were found on the lawn edges of the Tower of London gardens. London rocket was also found around London Zoo in Regent’s Park, but it is unknown whether it still exists here. There are records from Brentford, Roehampton and Deptford recorded in The Flora of London Area (Burton, 1983).
How to spot
London Rocket, Sisymbrium irio, is a non-native winter annual mustard with bright or pale yellow flowers. It is difficult to distinguish, but if you’re confident that you have seen the rare plant near you, do let us know!
Appearance and confusing species
The stems grow up to 60cm tall, and are generally green but are occasionally tinged with purple. The broad and long lower leaves form a rosette at the base of the plant, while the upper leaves are smaller and thinner. The fruit is long and narrow and stays green when ripe. The younger pods rise higher than the flowers themselves and when dried, the fruit has small, red oblong seeds.
Where and when to see it
You can spot London rocket in the Tower of London gardens and also London Wall at Tower Gateway. It has open, slender stem branches and produces small flowers with pale yellow petals, from January to May.
Content Where
When
Fascinating fact
London rocket was used in the Middle East to treat coughs and chest congestion, to relieve rheumatism, to detoxify the liver and spleen, to reduce swelling and to clean wounds.