Arugula is a fast growing, cool season green. It is perfect for the early spring garden and also great for extending the season into fall. Two of the most commonly grown wild arugulas are: Diplotaxisx tenuifolia and Diplotaxisx integrifolia.
Arugula goes by many common names, which get applied to about 20 different species of greens. Almost all of them are in the Brassicaceae or cole crop family. The two most popularly grown types for culinary purposes are 'Wild Arugula'' (Diplotaxisx), the spicy, hot variety, and 'Cultivated Arugula' (Eruca vesicaria), a tamer version. Cultivated arugula has white flowers and oval leaves, often with a wavy serration. Wild arugula has yellow flowers and smooth or serrated leaves. It is more heat tolerant with a hotter flavor and stronger scented than a cultivated rocket. There are several species within the Diplotaxis genus. You'll find them labeled as wild rocket, wall-rocket, Rucola Selvatica, or Arugula Sylvetta.