This section is from the book "British Wild Flowers - In Their Natural Haunts Vol2-4", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
Though this plant is not found in any deposit in England it occurs in the Oak Zone abroad. It is confined to the North Temperate Zone, and found in Europe, N. Africa, and Ireland. It is absent from S. Lines, Renfrew, W. Ross, but is found on every other British coast-line directly open to the sea up to Shetland. It is also found in Ireland and in the Channel Islands.
Like Sea Kale, Sea Rocket, which is associated with it, is fond of sand and shingle, and it forms fairly wide patches in company with Samphire, Thrift, Sea Lavender, Seaside Bindweed, Sea Plantain, Saltwort, maritime sedges and rushes, etc.
Like Sea Kale, again, the Sea Rocket is a bushy, compact, shrubby plant, with branched stems, the branches being arranged in a zigzag manner. It is also fleshy, and has bluish-green leaves, in this case more linear-pinnatifid, or with the lobes divided nearly to the base, or else quite entire. It is quite smooth, and has much the same appearance and habit as a broccoli. According to Lesage the leaves of other plants when grown inland may become fleshy if treated with salt.
The (lowers are white, or purple, or lilac, in corymbs, and the flower-stalk is strong. The upper portion of the pod is spindle-shaped, the two joints are angular, the lower joint is smaller than the upper, the former being erect. The latter is pendent, and has two teeth at the base. The pods are square in section, and when ripe are ribbed.
The plant grows to a height of 9 in. or 1 ft. It is in flower from June to September. It is annual and reproduced by seed.
The anthers of the long stamens project slightly, and as pollen may thus fall on the stigma self-pollination may occur. The flowers are scented. Two honey-glands, as in Sea Kale, lie at the base of the long and short stamens respectively. It is also visited by numerous insects. There is as much chance of cross-pollination in this plant as in the Sea Kale. The flowers, white and purple, are about the same size, but the stigma is stalkless, and there is little to prevent self-pollination as it is below the anthers.
The Sea Rocket is dispersed by its own special mechanism. The pods do not open, but drop off, and the seeds germinate around the parent plant.
The Sand Dart (Agrotis ripae) is the only moth which feeds upon it in the caterpillar stage, and a beetle, Psylliodes marcida.
Linnaeus adopted the name Cakile from Serapion. Cakile is said to be the Arabic name of the plant, but the significance (as applied to this plant) is unknown, while the Latin maritima refers to the plant's habitat.
Its English name Sea Rocket is the only one. It was reputed to be cathartic by the old botanical writers.
Essential Specific Characters: 39. Cakile maritima, Scop. - A bushy plant with glaucous, fleshy leaves, rounded stem, glabrous, zigzag; flowers white or lilac, pouches with 2 seeds ensiform above.