Firethorn is a fast growing, evergreen shrub that originated from china  . It was first introduced to England by Robert Fortune, then cultivated in South Europe. Today it can be found in parts of africa as well as Northern America. The scientific name for firethorn is Pyracantha, and it is classified in the division Magnoliophyta , class Magnoliopsida, order Rosales, family Rosaceae. There are different kinds of firethorn each of which has a different scientific name as well. The kind found most in Northern America is Pyracantha Coccinea, commonly called scarlet firethorn. The map below shows where (green states) this plant can be found. Other kinds include Pyracantha angustifolia (narrowleaf firethorn) and Pyracantha crenulata found in the US only in CaliforniaPyracantha fortuneana (Chinese firethorn) found in Florida and Alabama, and Pyracantha koidzumii (Formosa firethorn) found in Florida and South Carolina .
Firethorn has 1-2 inch long leaves and creamy white flowers that appear in May-June. These flowers are hermaphrodites and are pollinated by bees, and also attracted by butterflies and birds . The fruites of Firethorn occur in clusters of orange-red berries that ripen in summer and persist during winter .
Toxicity & Symptoms
firethorn is considered a poisonous plant. the berries are the most toxic part, and could cause vomitting, stomach ache, blistering of tongue, and diarrhea upon ingestion .The sap of the plant could also cause skin rash and irritation. Upon contact, one should immediately wash the affected area with water and soap. and in either case (ingestion or irritation) call his/her doctor.  Firethorn belongs to a genus where most, if not all the members produce the toxic poison hydrogen cyanide (HCN), which is what gives the berries their bitter taste. It is also the ingredient that causes skin irritationsv and is found mostly in the berries and the leaves. Ingestion of HCN can be fatal, however, since its concentration relatively low in the plant, it will only cause minor ilnesses as mentioned above. In very small quantities, HCN has shown to be rather beneficial in medical purposes..Hydrogen Cyanide
Another Toxin present in Firethorn is called maytansine, which is believed to be produced by microorganisms associated with the roots of the plant rather than the plant itself . Extracts of pyracantha also contain chloroform, acetic ether, and petroleum ether, which can be toxic at high concentrations, but again can have medical uses.The extracts have been used on mice and noticeably reduce blood coagulation time .
Hydrogen cyanide, also called hydrocyanic acid and prussic acid, is what causes plants such as bitter almonds, cherry laurel leaves and cassava to be poisonous. This fact was not known until the 18th century, and it was in 1782 when the Swedish chemist Scheele first isolated HCN from the dye Prussian Blue. He died 4 years later after breaking a vial of HCN. The formula was figured by Berthellot in 1787. 
Hydrogen cyanide is synthesized commercially by the reaction of methane with ammonia in the presence of a platinum catalyst .
There are however other ways in which HCN can be produced. For example, it can be manufactured by the catalytic decomposition of formamide, by enzymatic hydrolysis of nitriles and related chemicals or by treating cyanide salts with acid .An example is the reaction shown below:
NaCN (s) + HCl (aq) fi NaCl ( aq) + HCN (g)
Medical and other uses:
In small quantities, hydrogen cyanide has been shown to stimulate respiration and improve digestion, and research also shows it could be beneficial in the treatment of cancer.
Hydrogen cyanide is used in fumigating; electroplating; mining; and in producing synthetic fibers, plastics, dyes, pesticides and also used as an intermediate in chemical syntheses.
Hydrogen Cyanide was used during the Holocaust to kill masses of prisoners by Hitler's orders. It was also used by Iraq in the 1980's against Iran as well as Kurds in North Iraq.
The structure is shown below:
Maytansine was first isolated from the African plant Maytenus ovatus, later named Maytenus serrata in 1972 by Kupchan and co-workers. Certain other plants are however better sources of this substance, such as Maytenus buchannanii. Collections of these plants have been made in purpose of high yields of Maytansine to then use it for preclinical toxycology and cinical trials. The cost for this substance was estimated $75,000/g. 
The structure of Maytansine has been studied and derivatives have been synthesized including maytanbutine, maytanprine, and maytanvaline, which show similar activities as Maytansine.One of the ester carbons plays a very important role in the stereochemistry on this molecule. If it is reversed for example, the activity of the molecule noticeably decreases. Derivatives of Maytansine have been synthesized with this stereochemistry, including maytansinol and maysine 
Bibliography:Medical & Other uses:Therapeutic Purposes:
In some clinical trials Maytansine showed antileukemic activity against the P388 lymphocytic leukemia in mice and cytotoxicity against the KB cell culture derived from a human epidermoid carcinoma of the mouth. Maytansine also inhibits motosis by inhibiting tubulin polymerization, interfering with formation of microtublues, and therefore prevents DNA, RNA, and protein synthesis, with DNA synthesis most effected. This property made Maytansine a leading candidate for clinical trials that started in 1975, even though the toxicity of the substance caused certain problems, such as gastrointestinal toxicity, chronic toxicity in many tissues, neurotoxicity, inflammation, and fibrosis. Patients suffering from acute lymphocytic leukemia, breast carcinoma, ovarian cancer, thymoma, melanoma, and non-small scale lung cancer all responded to certain levels, but the severe pains caused by Maytansine, especially the neurotoxicity cause at the site of injection, lead to the petients refusing the treatment, and so Maytansine was dropped from clinical trials. 
Firethorn also has flavonoids and proanthocyanidins including Luteolin, luteolin-3', 7-diglucoside, apigenin, apigenin-7-O-glucoside and rutin. These compounds show antioxidant activity, and are toxic because of the high tendency to react, but also have many medical uses.Apigenin for example, has shown to inhibit the growth of breast carcinoma cells , human thyroid cancer cells, and human prostate tumors. Apgenin, as well as luteolin (another flavonoid), show more effectiveness than the currently common prescribed oral contraceptives (Ortho-Novum, Medicon and LO/OVRAL) in preventing pregnancy. they were also found to be toxic against the methicillin-resistant bacteria, Staphylococcus aureus.
 http://www.hear.org/weedlists/other_areas/nz/nzecoweeds.htmhttp://www.people.vcu.edu/~asneden/Maytansine.pd http://www.people.vcu.edu/~asneden/Maytansine.pdff