General: London Rocket Mustard (Sisymbrium irio) is an annual forb with basal leaves, several flowering stalks, and tiny, yellow, 4-petaled flowers. The basal leaves are dissected with 6-14 pairs of lateral lobes, and the terminal lobe is about the size of lateral lobes. New seed pods overtop new flowers. The plant dies after it flowers, leaving open, upright stalks that are highly flammable.

London Rocket Mustard is an uncommon component of disturbed desert vegetation communities. Around Las Vegas, look for this species in town and in disturbed roadsides and open fields. This is a fairly recent addition to our local flora. The name "rocket' is appropriate because it grows and spreads rapidly.

Family: Mustard (Brassicaceae).

Other Names: Desert Mustard

Plant Form: Plants remain as rosettes until they develop flowering stems at maturity. Basal leaves with upright, leafy flower stalks.

Height: To about 3 feet.

Stems: Several flowering stalks mostly originating near the base. Stems glabrous or sparsely hairy; without stiff hairs.

Leaves: Generally basal; generally broad and dissected (pinnately lobed) with 6-14 pairs of lateral lobes; terminal lobe about the size of lateral lobes. Upper leaves are smaller and oblong (not lobed).

Flowers: Blooms during early spring. Flowers clustered at the top of the flower stalks; petals 4, yellow. Petals short and narrow (less than 4 mm long, 1-1.5 mm wide). Sepals about 2 mm long.

Fruit: Long (30–40 mm), narrow pod (cylindrical silique), constricted between seeds, remains green when ripe; seeds 40–90. New pods overtop flowers. Spreading from stem. Pedicels narrower than fruit.

Seeds: Tiny (1-mm wide), oblong.

Habitat: Roadsides, picnic areas, disturbed sites; spreading into undisturbed desert sites.

Elevation: To about 3,000 feet (<1500 m); usually lower elevations.

Distribution: California to Texas and south into Mexico. Native to the Mediterranean region.

Comments: This species is similar to Black Mustard and Sahara Mustard.

The leaves, seeds, and flowers are edible when young, with a spicy flavor