Common Name: Rattlebush

General Information

Sesbania drummondii is a perennial plant with stems that become more or less woody, especially near the base; it can grow up to 4 metres tall[].
The plant has potential for use as a biomass crop and hyperaccumulator plant on sites contaminated with heavy metals. It is occasionally grown as an ornamental.
Sesbania drummondii is widespread and common in its natural range. It is known to occur within the protected area network and there are no major threats to the species at present, therefore the population is believed to be stable. The plant is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2013)[].

Known Hazards

As the seeds mature, they become loose in the pods and rattle when moved[]. They contain sesbanimide, and are poisonous when eaten, affecting humans and various grazing animals - the toxins are probably saponins. The symptoms include diarrhoea, weakness, lethargy and sometimes death[].
Although poisonous, saponins also have a range of medicinal applications and many saponin-rich plants are used in herbalism (particularly as emetics, expectorants and febrifuges) or as sources of raw materials for the pharmaceutical industry. Saponins are also found in a number of common foods, such as many beans.
Saponins have a quite bitter flavour and are in general poorly absorbed by the human body, so most pass through without harm. They can be removed by carefully leaching in running water. Thorough cooking, and perhaps changing the cooking water once, will also normally remove most of them. However, it is not advisable to eat large quantities of raw foods that contain saponins.
Saponins are much more toxic to many cold-blooded creatures, such as fish, and hunting tribes have traditionally put large quantities of them in streams, lakes etc in order to stupefy or kill the fish and make them easy to catch[].

Botanical References

Range

Southern N. America - northern Mexico, through Texas to Florida and South Carolina

Habitat

Mainly found in coastal areas, growing on sand dunes, on low wet grounds, frequently-inundated meadows and also in disturbed habitats such as along roadsides; at elevations up to 100 metres[].

Properties

Conservation Status	Least Concern
Habit	Shrub
Height	2.50 m
Growth Rate	Fast
Pollinators	Bees
Cultivation Status	Cultivated, Ornamental

Cultivation Details

Sesbania drummondii is a subtropical plant and is not very cold tolerant, being damaged by temperatures down to around -4°c. In mild winter areas, although top growth may be killed off, the plant will often resprout from the lower 30 - 50cm of the stem.
Requires a sunny position, growing best in moist to wet soils.
Plants grow rapidly from seed and will usually flower in their second year.
Heavy pruning after flowering will often induce a second flush of flowers.
Similar to Sesbania punicea, the two species are known to hybridize in cultivation.
This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby[].

Edible Uses

None known

Medicinal

None known

Agroforestry Uses:

The plant can hyperaccumulate toxic metals including lead and cadnium[]. It has been shown to accumulate more than 4% lead in its shoots and , with its high bulk of organic matter, has potential for use in phytoremetiation projects where it can help to remove toxic metals whilst also rebuilding ssoil structure[].

Other Uses

None known

Propagation

Seed - it has a hard seedcoat and benefits from scarification before sowing in order to speed up and improve germination. This can usually be done by pouring a small amount of nearly boiling water on the seeds (being careful not to cook them!) and then soaking them for 12 - 24 hours in warm water. By this time they should have imbibed moisture and swollen - if they have not, then carefully make a nick in the seedcoat (being careful not to damage the embryo) and soak for a further 12 hours before sowing.