Species Guide: Common Nitrogen-Fixing Plants

Sunn Hemp

Sunn hemp plants with their green, narrow leaves. Photo by Khim Joe

Common name: Sunn Hemp

Malay name: 

Scientific name: Crotalaria juncea

Conservation status: Cultivated, Naturalised, Introduced (India)


An evergreen shrub that grows up to 2.5 m tall. It has a straight stem and hairy branches. Leaves are narrow and spirally arranged. It bears yellow, pea-like flowers and short, puffy seedpods.

A patch of leafy sunn hemp. Photo by Khim Joe
Note the yellow flowers of sunn hemp. Photo by Khim Joe

Habit: Annual shrub

Cultivation: It is planted by seeds

Ecological function:  This plant is used as green manure. It is planted as a cover crop to suppress weeds. It fixes nitrogen in soil. Its flowers attract pollinators.

Pollinator: Bees, insects

Soil: Sand, loam, clay

Moisture: Moist, well-drained soils. Established plants are drought-tolerant

Shade: No shade

Use: Edible (leaf, flower), fibre (paper, string, fishing net)

By ShangMing

A plant lover. I like small, medium, gigantic, ordinary, exotic, local, foreign plants. Just because they thrive to stand out.