Barbarea vulgaris, also called bittercress, herb barbara, rocketcress, yellow rocketcress, winter rocket, yellow rocket, and wound rocket, is a biennial herb of the genus Barbarea, belonging to the family Brassicaceae.
Description
This plant grows to about high, with a maximum of. The stem is ribbed and hairless, branched at the base. It has basal rosettes of shiny, dark green leaves. The basal leaves are stalked and lyre-pinnatifid, that is with a large terminal lobe and smaller lower lobes. The cauline leaves are smaller, ovate, toothed, or lobed. The flowers are borne in spring in dense terminal clusters above the foliage. They are long, with four bright yellow petals. The flowering period extends from about April through July. The fruit is a pod around. Chemical substances in this species include saponins, flavonoids, and glucosinolates.
Taxonomy
It was first published and described by William Aiton in his 'Hortus Kewensis' Vol.4 on page 109 in 1812. Some references mention Robert Brown, as the author but there are no mentions of his name in Hortus Kewensis, so Aiton is regarded as the correct author. It has various common names including 'bittercress', 'cressy-greens', 'herb-Barbaras', 'rocket cress', 'upland cress', 'English wintercress' and 'yellow rocket'.
Etymology
The genus name Barbarea derives from Saint Barbara, the patron saint of artillerymen and miners, as this plant in the past was used to soothe the wounds caused by explosions. The species Latin namevulgaris means “common”.
Natural insect resistance and its potential use in agriculture
Most B. vulgaris genotypes are naturally resistant to some insect species that are otherwise specialized on the crucifer family. In the case of diamondback moth and the flea beetlePhyllotreta nemorum, the resistance is caused by saponins. Glucosinolates such as glucobarbarin and glucobrassicin are used as a cue for egg-laying by female cabbage white butterflies such as Pieris rapae. Indeed, the larvae of this butterfly thrive well on this plant. Diamondback moth females are also stimulated by these chemicals, but the larvae die due to the content of saponins which are apparently not sensed by the moths. This phenomenon has been tested for biological insect control: B. vulgaris plants are placed in a field and attract much of the diamondback moth egg load. As the larvae die shortly after hatching, this kind of insect control has been named "dead-end trap cropping".
The plant prefers fresh or moist places, on roadsides, along rivers, in arable land, wastelands and docklands, or on the slopes and in ditches, at an altitude of above sea level. It also prefers to grow in siliceous, calcareous, sandy, alluvial and clay soils.
Natural chemotypes with distinct ecology
A pubescent type has been described from southern Scandinavia and Russia. While this chemotype is rare in Scandinavia, it seems to be dominant in Russia according to the only survey made so far. This type has atypical chemistry and is devoid of resistance to the diamondback moth and the flea beetle Phyllotreta nemorum. The P-type belongs morphologically to the variety B. vulgaris var. arcuata, but may also be identical to the subspecies originally described as Barbareaarcuata Rchb. ssp. pubescens N. Busch. In this context, the usual type of B. vulgaris var. arcuata is called the "G-type". This type is reported to be dominant in Central Europe. On a genomic scale, more than 22.000 genes were found to have fixed differences between the two types. A chemotype with deviating glucosinolate content has been described from Western and Central Europe and named the "NAS-type". While the P-type and G-type differ in multiple genetic, chemical and morphological features, the NAS and BAR types seem to be a simple monogenic variation. For this reason, it has been suggested to refer to NAS and BAR forms and P- and G-types. Indeed, occasional NAS form plants in Central Europe were found to be G-type by a set of genetic markers.
