Nux vomica is a tree native to India and Southeast Asia. The tree has a short crooked trunk and smooth, ash-coloured bark. The leaves are oval and shiny, and the flowers small, greenish-white, and funnel shaped, with, it is said, "a disagreeable smell". The fruits of the tree are the size of an apple with a hard rind that becomes orange when ripe; they are filled with a white jelly-like pulp and contain five seeds; it is this part of the plant that is harvested. They are removed when ripe, cleaned, and dried, and exported; they are flat disks covered with short satiny hairs which gives them a sheen. The seeds are very hard and have no odour, but are very bitter in taste. From these seeds are derived the very poisonous alkaloids strychnine and brucine. Other names for the seeds are poison nuts, semen strychnos, dog buttons, and, most oddly of all, Quaker buttons.
Nux vomica used to be used in weak dosages in herbal medicine, particularly for disorders of the gastro-hepatic tract, as it has an emetic, stimulating effect often associated with bitters. (In layperson's language, it makes you puke.) Modern homeopathic practitioners may prescribe nux vomica for indigestion, headaches and the like which are caused by too much food, coffee, alcohol, or drugs, which may also make the patient overly sensitive and given to anger and irritability. Nux vomica should never be taken in large quantities, for strychnine poisoning is extremely unpleasant and can be fatal.
http://www.botanical.com/botanical/mgmh/n/nuxvom08.html
http://www.naturalnet.com/nux.html
http://www.ibiblio.org/herbmed/eclectic/potter-comp/strychnos-nux.html
http://www.internethealthlibrary.com/hom-library/nux-vomica.htm