of the valley
It is a creeping
plant up to 6 m long and has 15-cm long fruits. Its seeds are dark brown,
kidney-shaped and very similar to ordinary beans, which is why they cause
accidents very often. They are extremely poisonousone seed is enough to
kill a person.
Local people are familiar
with the toxic effect of this plant. They used it in the public trials
to challenge the innocence of the accused by administering a poison prepared
from Calabar bean. Surviving this poisoning was considered a proof of innocence
but it was an extremely rare occasion.
Its medical significance
was discovered in 1855, who received some seeds from an African missioner
to facilitate his research. Nowadays, the seeds of Physostigma venenosum
are used as a source of the valuable alkaloid physostigmin. Its application
is limited to ophthalmology and toxicology. It is also effective in cases
of diseases of the peripheral nervous system, muscle and bowel diseases
but its usage is now limited because of its toxicity.