Senna

Senna hebecarpa, commonly known as wild senna, is a North American native plant growing on damp soils in Ontario, the east coast of the United States, south to Georgia and as far west as Wisconsin. Despite its vigour and mass production of seeds (of which only 10-30% are viable) in cultivated situations, this plant is considered endangered. Wild senna grows along roadways, disturbed areas, fields and the edge of streams. However, changes in hydrology, development of land and succession of secondary species are thought to be reducing its numbers.

Medicinal uses of Senna hebecarpa are extensive, ranging from curing cramps to administering for fainting spells.

The extensive collecting of this plant for medicinal purposes (PDF) is also thought to contribute to the decline of this species in the wild.

How to grow Wild Senna - Cassia
If planning to grow Cassia outdoors from the off it is best to sow out the seed in either Summer or autumn at a depth of 3mm. Wild Senna like species should be grown in soil that has good drainage, in either a sunny or partly shaded part of the garden. When growing Cassia indoors first then you will first need to chip the seeds, then soak in warm water for three hours before sowing. They should be planted about 7 weeks before you transplant the seedlings outdoors, in the autumn or after the last frost of the spring. When putting the seedlings out they should be spaced at about 60 to 90cm apart.
Caring for Cassia
Once established Cassia requires regular fertilisation and watering; ideally they should be thinned in the autumn.

sourced from:

http://www.plant-biology.com/Cassia-wild-senna.php

www.ubcbotanicalgarden.org