Spicy young ‘rocket’ (Eruca sativa – BRASSICACEAE) leaves are an easy addition to summer salads, or they can be used alone in a peppery salad with sliced pear and shaved parmesan cheese drizzled with olive oil.
Many Italian restaurants serve ‘wild rocket’ (‘Arugula’ in Italian, ‘Roquette’ in French), which has thinner leaves than the standard ‘cultivated rocket’ more commonly found in green-groceries. While the wild rocket has a distinctive flavour, you will get a bigger salad from the leafier cultivated rocket.
The former has a yellow flower, while the latter has a white flower with purple veins. Both varieties generate the flower at the top of a long stalk, with seed pods called ‘siliques’ forming along this stem on each old flower stalk. Once the flowers form (often accelerated by drought and high-temperatures) the leaves are too strong in flavour to be eaten.
Rocket is insect-pollinated, generally by bees, and does not cross-pollinate with other brassicas (members of the cabbage family, such as kale, cabbage, broccoli, mustard and kohl rabis).
Brassica seed appear at the end of the first growing season, and should be collected before the rains set in or the seed is spilled onto the ground by hot winds. The seeds rattle in the pod when dry. I find the simplest method is to strip them from the plant while it is still in the ground, straight into a bucket by dragging the dry stalks through the hand. Alternatively, break off the dry stems holding the siliques, and bang them against the side of a deep bucket to shake the seed loose. Then just throw away the dry seed husks. Many other seeds can be collected in the same fashion; this bucket full contains parsley seed as well as various brassicas.
The photo below shows a typical brassica seed pod, where the seeds are separated by a thin tissue-like layer into two rows on either side of the silique.
Brassicas such as Chinese cabbage can be grown from spring time onwards on the Adelaide plains, and we use them for leafy greens for the chooks. As this is essentially a low-value crop (though popular with bees and birds) the seed are bulked together and broadcast sown to save labour (provided ground is available). However, like European broccoli grown late into the warmer months, they attract ‘white fly’, which lay sticky grey eggs on these plants, making them unattractive and inedible.