Eastern Rocket - Sisymbrium orientale

A tall, branched weed with long (up to 12 cm) narrow pods. The lower rosette leaves are deeply lobed, but the degree to which the leaf is lobed decreases up the stem. The upper leaves are unlobed. All leaves have a distinct petiole. The stems, leaves and pods are slightly hairy with unbranched hairs. The flowers are yellow, with petals about twice the length of the sepals.

other Sisymbrium

Seed-pods long and sticking out from stem, without beak, splitting into 2 valves with one row of seeds in each valve; lowest leaves lobed, upper stem-leaves divided but not pinnate; fruit pedicels a lot narrower than ripe fruit, lower part of stem with stiff hairs.  

Photos of leaves (basal and stem leaves) and ripe fruit

A weed of wasteland and waste places, frequently found growing out of the cracks in city streets.

In flower during June, July and August.

Annual.

Occasional plant that is widely scattered over much of Britain

Occasional in Leicestershire and Rutland where it is most often found in built up areas. In the 1979 Flora survey of Leicestershire it was found in 27 of the 617 tetrads.

In the current checklist (Jeeves 2011) is is Alien, neophyte, occasional