"Sissinghurst" have gained the Royal Horticultural Society's Award of Garden Merit. Pests and diseases For some verbena pathogens, see List of verbena diseases. Cultivated verbenas are sometimes parasitized by sweet potato whitefly (Bemisia tabaci) and spread this pest to other crops. Uses Although verbena ("vervain") has been used in herbalism and traditional medicine, usually as an herbal tonic, there is no high-quality evidence for its effectiveness. Verbena has been listed as one of the 38 plants used to prepare Bach flower remedies, a kind of alternative medicine promoted for its effect on health. According to Cancer Research UK, "essence therapists believe that using essences can help to increase your mental, emotional and spiritual wellbeing. However, essences are not used to prevent, control, or cure cancer or any other physical condition." The essential oil of various species, mainly common vervain, is traded as "Spanish verbena oil". Considered inferior to oil of lemon verbena (Aloysia citrodora) in perfumery, it is of some commercial importance for herbalism. In culture Verbena has long been associated with divine and other supernatural forces. It was called "tears of Isis" in ancient Egypt, and later called "Hera's tears". In ancient Greece it was dedicated to Eos Erigineia. The generic name is the Latin term for a plant sacred to the ancient Romans. Pliny the Elder describes verbena presented on Jupiter altars; it is not entirely clear if this referred to a verbena rather than the general term for prime sacrificial herbs. Pliny the Elder notes "the Magi especially make the maddest statements about the plant: that [among other things] a circle must be drawn with iron round the plant". The common names of verbena in many Central and Eastern European languages often associate it with iron. These include for example the Dutch ("iron-hard"), Danish ("medical ironwort"), German ("true ironherb"), Slovak ("medical ironherb"), and Hungarian ("iron grass"). In the early Christian era, folk legend stated that V. officinalis was used to staunch Jesus' wounds after his removal from the cross. It was consequently called "holy herb" or (e.g. in Wales) "Devil's bane". According to the Wiccan writer Doreen Valiente, Vervain flowers signify the goddess Diana and are often depicted on cimaruta, traditional Italian amulets. In the 1870 The History and Practice of Magic by "Paul Christian" (Jean-Baptiste Pitois) it is employed in the preparation of a mandragora charm. The book also describes its antiseptic capabilities (p. 336), and